Oc_authtoken.ibd growing out of control

Nextcloud version 16.0.3:
Operating system and version CentOS 7:
Apache or nginx version Apache 2.4.6:
PHP version 7.3.13:

I’m running a little VPS server for 4 family members and 2 friends.

It has 6 NextCloud installations, each under a separate TLD to create a complete separation of accounts.

One of the users has less than 1gb of data stored, yet, his oc_authtoken.ibd file:

full path /var/lib/mysql/USERNAME/oc_authtoken.ibd

is over 41gb - and growing.

How do I fix this without a full reinstallation?