PHP error on upgrade via fresh install

I have Nextcloud 19.0.4.2 running in Ubuntu LTS 18.04. Since the new NC requires a new php, I thought it’d be easier to just create a new VM to install the new version on. So I created an Ubuntu 20.04 environment to install NC 21.0.0. Went through the manual install (since that’s recommended), stopped NC 19, moved the config et al over, and tried to connect.

Below is the error I get on “sudo -u www-data php occ upgrade”. Any advice would be appreciated!

{"reqId":"bE7KgaWhcexPBMBM3wE8","level":0,"time":"2021-03-07T18:57:46+00:00","remoteAddr":"","user":"--","app":"support","method":"","url":"--","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"--","version":"21.0.0"}
PHP Fatal error:  Class OCA\Support\Subscription\SubscriptionAdapter contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (OCP\Support\Subscription\ISubscription::isHardUserLimitReached) in /var/www/nextcloud_static/apps/support/lib/Subscription/SubscriptionAdapter.php on line 30
{"reqId":"bE7KgaWhcexPBMBM3wE8","level":3,"time":"2021-03-07T18:57:46+00:00","remoteAddr":"","user":"--","app":"PHP","method":"","url":"--","message":"Class OCA\\Support\\Subscription\\SubscriptionAdapter contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (OCP\\Support\\Subscription\\ISubscription::isHardUserLimitReached) at /var/www/nextcloud_static/apps/support/lib/Subscription/SubscriptionAdapter.php#30","userAgent":"--","version":"21.0.0"}

Forum disclaimer: Not entirely sure if this should be in Installation or upgrade, since it’s a fresh install connecting to a pre-existing database.

Also wanted to note that all the other posts on this said “reinstall php modules” (which makes sense since there’s a new version oh php). Since this was a fresh manual install, it should be clear this does not apply to me.