Same issue here. Example error log:
{"reqId":"9u4T6xN31IAIGWECaJMh","level":3,"time":"16 July 2024 08:55:04","remoteAddr":"","user":"--","app":"mail","method":"","url":"--","message":"Cron mail sync failed for account 1","userAgent":"--","version":"29.0.3.4","exception":{"Exception":"OCA\\Mail\\Exception\\ServiceException","Message":"Sync failed for 1:INBOX: Call to undefined function ini_restore()","Code":0,"Trace":[{"file":"/home/user/nextcloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php","line":137,"function":"sync","class":"OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/apps/mail/lib/BackgroundJob/SyncJob.php","line":110,"function":"syncAccount","class":"OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/Job.php","line":80,"function":"run","class":"OCA\\Mail\\BackgroundJob\\SyncJob","type":"->"},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/TimedJob.php","line":102,"function":"start","class":"OCP\\BackgroundJob\\Job","type":"->"},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/TimedJob.php","line":92,"function":"start","class":"OCP\\BackgroundJob\\TimedJob","type":"->"},{"file":"/home/user/nextcloud/cron.php","line":177,"function":"execute","class":"OCP\\BackgroundJob\\TimedJob","type":"->"}],"File":"/home/user/nextcloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php","Line":280,"Previous":{"Exception":"Error","Message":"Call to undefined function ini_restore()","Code":0,"Trace":[{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-util/lib/Horde/String.php","line":99,"function":"_convertCharset","class":"Horde_String","type":"::"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime.php","line":254,"function":"convertCharset","class":"Horde_String","type":"::"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Headers/Element/Single.php","line":62,"function":"decode","class":"Horde_Mime","type":"::"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Headers/Element.php","line":79,"function":"_setValue","class":"Horde_Mime_Headers_Element_Single","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Headers/Element.php","line":56,"function":"setValue","class":"Horde_Mime_Headers_Element","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Headers/Subject.php","line":31,"function":"__construct","class":"Horde_Mime_Headers_Element","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Headers.php","line":201,"function":"__construct","class":"Horde_Mime_Headers_Subject","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Data/Envelope.php","line":160,"function":"addHeader","class":"Horde_Mime_Headers","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":3519,"function":"__set","class":"Horde_Imap_Client_Data_Envelope","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":3169,"function":"_parseEnvelope","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":4796,"function":"_parseFetch","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":4593,"function":"_serverResponse","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":4319,"function":"_getLine","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":4243,"function":"_sendCmdChunk","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php","line":2839,"function":"_sendCmd","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php","line":2737,"function":"_fetch","class":"Horde_Imap_Client_Socket","type":"->"},{"file":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php","line":2493,"function":"_fetchWrapper","class":"Horde_Imap_Client_Base","type":"->"},{"file":"/home/user/nextcloud/apps/mail/lib/IMAP/MessageMapper.php","line":284,"function":"fetch","class":"Horde_Imap_Client_Base","type":"->"},{"function":"OCA\\Mail\\IMAP\\{closure}","class":"OCA\\Mail\\IMAP\\MessageMapper","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/apps/mail/lib/functions.php","line":35,"function":"array_map"},{"file":"/home/user/nextcloud/apps/mail/lib/IMAP/MessageMapper.php","line":283,"function":"OCA\\Mail\\array_flat_map"},{"file":"/home/user/nextcloud/apps/mail/lib/IMAP/Sync/Synchronizer.php","line":100,"function":"findByIds","class":"OCA\\Mail\\IMAP\\MessageMapper","type":"->"},{"file":"/home/user/nextcloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php","line":398,"function":"sync","class":"OCA\\Mail\\IMAP\\Sync\\Synchronizer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php","line":261,"function":"runPartialSync","class":"OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer","type":"->"},{"file":"/home/user/nextcloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php","line":137,"function":"sync","class":"OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/apps/mail/lib/BackgroundJob/SyncJob.php","line":110,"function":"syncAccount","class":"OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/Job.php","line":80,"function":"run","class":"OCA\\Mail\\BackgroundJob\\SyncJob","type":"->"},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/TimedJob.php","line":102,"function":"start","class":"OCP\\BackgroundJob\\Job","type":"->"},{"file":"/home/user/nextcloud/lib/public/BackgroundJob/TimedJob.php","line":92,"function":"start","class":"OCP\\BackgroundJob\\TimedJob","type":"->"},{"file":"/home/user/nextcloud/cron.php","line":177,"function":"execute","class":"OCP\\BackgroundJob\\TimedJob","type":"->"}],"File":"/home/user/nextcloud/apps/mail/vendor/bytestream/horde-util/lib/Horde/String.php","Line":161},"message":"Cron mail sync failed for account {accountId}","exception":{},"CustomMessage":"Cron mail sync failed for account 1"}}