Having worked out how to get the thing to log, this has now been recorded:
{“reqId”:“xKcivKMj2DJkoedJO17A”,“level”:0,“time”:“April 03, 2021 20:33:02”,“remoteAddr”:“...",“user”:"–",“app”:“files_sharing”,“method”:“POST”,“url”:"/nextcloud/index.php/login",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“iuvtlcLD0hPD6ILQaCPV”,“level”:0,“time”:“April 03, 2021 20:33:02”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/index.php/core/apps/recommended",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“iuvtlcLD0hPD6ILQaCPV”,“level”:0,“time”:“April 03, 2021 20:33:02”,“remoteAddr”:"...",“user”:"–",“app”:“core”,“method”:“GET”,“url”:"/nextcloud/index.php/core/apps/recommended",“message”:{“Exception”:“OC\AppFramework\Middleware\Security\Exceptions\NotLoggedInException”,“Message”:“Current user is not logged in”,“Code”:401,“Trace”:[{“file”:"/var/www/nextcloud/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php",“line”:98,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\Security\SecurityMiddleware”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",“line”:119,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\MiddlewareDispatcher”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/AppFramework/App.php",“line”:157,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/Route/Router.php",“line”:302,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::"},{“file”:"/var/www/nextcloud/lib/base.php",“line”:993,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->"},{“file”:"/var/www/nextcloud/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::"}],“File”:"/var/www/nextcloud/lib/private/AppFramework/Middleware/Security/SecurityMiddleware.php",“Line”:143,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“Hh8auahcHqfYjVG4B61A”,“level”:0,“time”:“April 03, 2021 20:33:02”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/index.php/login?redirect_url=/nextcloud/index.php/core/apps/recommended",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“VdX4tAN9TMhy7KmiIsKB”,“level”:0,“time”:“April 03, 2021 20:33:03”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“VdX4tAN9TMhy7KmiIsKB”,“level”:0,“time”:“April 03, 2021 20:33:03”,“remoteAddr”:"...",“user”:"–",“app”:“cron”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:“Run OCA\Files_Sharing\BackgroundJob\FederatedSharesDiscoverJob job with ID 4”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“VdX4tAN9TMhy7KmiIsKB”,“level”:0,“time”:“April 03, 2021 20:33:03”,“remoteAddr”:"...",“user”:"–",“app”:“cron”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:“Finished OCA\Files_Sharing\BackgroundJob\FederatedSharesDiscoverJob job with ID 4 in 0 seconds”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“dZyxZSubwNHCn43L1v66”,“level”:0,“time”:“April 03, 2021 20:33:17”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“POST”,“url”:"/nextcloud/index.php/login",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“JDO3vwpP3GZqK4qMIf1q”,“level”:0,“time”:“April 03, 2021 20:33:17”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/index.php/core/apps/recommended",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“JDO3vwpP3GZqK4qMIf1q”,“level”:0,“time”:“April 03, 2021 20:33:17”,“remoteAddr”:"...",“user”:"–",“app”:“core”,“method”:“GET”,“url”:"/nextcloud/index.php/core/apps/recommended",“message”:{“Exception”:“OC\AppFramework\Middleware\Security\Exceptions\NotLoggedInException”,“Message”:“Current user is not logged in”,“Code”:401,“Trace”:[{“file”:"/var/www/nextcloud/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php",“line”:98,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\Security\SecurityMiddleware”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",“line”:119,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\MiddlewareDispatcher”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/AppFramework/App.php",“line”:157,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->"},{“file”:"/var/www/nextcloud/lib/private/Route/Router.php",“line”:302,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::"},{“file”:"/var/www/nextcloud/lib/base.php",“line”:993,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->"},{“file”:"/var/www/nextcloud/index.php",“line”:37,“function”:“handleRequest”,“class”:“OC”,“type”:"::"}],“File”:"/var/www/nextcloud/lib/private/AppFramework/Middleware/Security/SecurityMiddleware.php",“Line”:143,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“Uc1yOSx4eQt7sAU54HIs”,“level”:0,“time”:“April 03, 2021 20:33:17”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/index.php/login?redirect_url=/nextcloud/index.php/core/apps/recommended",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“vh8aMIsvcsoly7Vt0hg2”,“level”:0,“time”:“April 03, 2021 20:33:18”,“remoteAddr”:"...",“user”:"–",“app”:“files_sharing”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:"/appinfo/app.php is deprecated, use \OCP\AppFramework\Bootstrap\IBootstrap on the application class instead.",“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“vh8aMIsvcsoly7Vt0hg2”,“level”:0,“time”:“April 03, 2021 20:33:18”,“remoteAddr”:"...",“user”:"–",“app”:“cron”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:“Run OCA\DAV\BackgroundJob\CleanupDirectLinksJob job with ID 5”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}
{“reqId”:“vh8aMIsvcsoly7Vt0hg2”,“level”:0,“time”:“April 03, 2021 20:33:18”,“remoteAddr”:"...**”,“user”:"–",“app”:“cron”,“method”:“GET”,“url”:"/nextcloud/cron.php",“message”:“Finished OCA\DAV\BackgroundJob\CleanupDirectLinksJob job with ID 5 in 0 seconds”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0”,“version”:“21.0.0.18”}