I don't know what fixed it, but it works for me again: akonadi-backend-mysql 4:22.04.3-1 akonadi-server 4:22.04.3-1 kontact 4:22.04.3-1 libkf5libkdepim5:amd64 4:22.04.3-1 libqt5sql5-mysql:amd64 5.15.4+dfsg-5 mariadb-server 1:10.6.9-1
Thanks a lot to whoever fixed it! <3