Probably not the right place to make bug reports, and this one is very minor since it's easy to max potency anyway, but
At the point in progression where you first get the anal option for sabatha (second time visiting them in your lair I think?) if you choose to repeat the oral scene instead, you'll still get a potency increase at the end.
Since visiting doesn't progress toward the end of the act, this can be repeated for infinite potency.