Checking posts on this site that hadn't been resolved I came across one of mine:- Cleanup Tools
https://forums.b2evolution.net/cleanup-tools

Checking out the issue, as I have upgraded to 7.1.6, I found that the first three options under Cleanup tools still didn't have a [Back to tools menu] option, but what has now transpired is that I get an error on the first of these options > Cleanup tools > Find and delete all orphan Tag entries (not used anywhere) - DB only.

This is similar to a mismatch in another more recent post of mine that happened upgrading from 7.1.6 to 7.2.0
https://forums.b2evolution.net/7-1-6-to-7-2-9-database

The database seems fine using : Check/Convert/Normalize the charsets/collations used by the DB (UTF-8 / ASCII)