Thank you for taking the time to file a bug report.
From the logs we can see:
mysqld is running as pid 16349
Error: Unable to shut down server with process id 16349
Do you have by any chance another mysqld process running not managed by
the Debian package provided by Ubuntu? I am asking that
** Tags removed: need-duplicate-check
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https://bugs.launchpad.net/bugs/1938640
Title:
package mysql-server-8.0 8.0.26-0ubuntu0.20.04.2 failed to
install/upgrade: installed
