You might face an increase of the file /var/lib/fail2ban/fail2ban.sqlite3

Here few commands that allows you to dig within the db, and clean up some rows, reducing its size.

Open the db:
sqlite3 /var/lib/fail2ban/fail2ban.sqlite3

Now, check all the tables available:
sqlite> .tables
bans fail2banDb jails logs

Generally, the “bans” table is the one that uses more space. You can check the content of this table using some SELECT statements like:
sqlite> SELECT * FROM bans limit 1;
With this, you can check one single row, and all its parts and content.

If you identify, for example, that there are very old entries (in my case, entries from 2 years ago, from 2018 and 219), you can trim all those entries with this command:
sqlite> DELETE FROM bans WHERE DATE(timeofban, 'unixepoch') < '2020-01-01'; VACUUM;

After running the above command, I got my db shrank.
A restart of fail2ban services will reload the db and release the space of the previous db.

Sources:
https://jim-zimmerman.com/?p=1234
https://serverfault.com/questions/1002315/fail2bans-database-is-too-large-over-500mb-how-do-i-get-it-to-a-reasonable-s