Hi Tinder,
I had a look at your log file. Near the bottom it says:
2022-09-25 20:49:34,594: INFO - + Processing triggers for mariadb-server-10.3 (1:10.3.36-0+deb10u1) ...
2022-09-25 20:49:34,723: WARNING - postinst called with unknown argument 'triggered'
2022-09-25 20:49:34,761: WARNING - dpkg: error processing package mariadb-server-10.3 (--configure):
2022-09-25 20:49:34,763: WARNING - installed mariadb-server-10.3 package post-installation script subprocess returned error exit status 1
2022-09-25 20:49:34,775: WARNING - Errors were encountered while processing:
2022-09-25 20:49:34,777: WARNING - mariadb-server-10.3
2022-09-25 20:49:34,955: WARNING - E: Sub-process /usr/bin/dpkg returned an error code (1)
Since about a week more people encounter this postinst called with unknown argument 'triggered', myself included.
In the Matrix-chat-room I read that tituspijean is investigating the issue. He found an upstream bug report.
From my experience with the problem: don’t try to solve it for the moment. If you can wait a while, leave the migration until the cause of the error or a workaround is found.
Is your MariaDB (and rest of your system) functional at the moment?