Ah, I think I know why this bug happens, and it most likely links to other mysteriously sticky Mod-value-related bugs that have been popping up recently. It's due to combat status effects being removed by time rather by the end-of-combat cleanup procedure. I had made an update where combat count-down effects would set their minutesLeft value so that the turn counter can be visible to the player for clarity. This had the unintended side effect of having the combat effect expire when time passes like normal status effects...
Since combat doesn't end right away after defeating the opponent, the time passage during a post-combat sex scene can improperly kill any active combat status effects that have over-0 minutes set, making the related stat-Mod changes stick instead reverting as it is intended to when combat officially ends (the part where you earn XP and pick up any loot, right before returning to the main text/navigation). Thank you for running into this bug, because I honestly believe this bug would have remained a mystery for some time given how status effects are handled.
I've found the where all status effects are handled and added an exception to combat-only effects to not be affected by time if they ever escape the combat's cleanup process (I had always assumed this was handled like this in the past, but apparently not). This should hopefully fix any future pre-mature deaths of combat-only status effects and everything should work as originally intended after the next release.
Unfortunately, there is no in-game fix to revert the value for your save (because the status effects no longer exists), so I would recommend manually setting the values via the browser console, if you can. In the console, you can type:
Code:
pc.physiqueMod = 0;
pc.reflexesMod = 0;
And, if there are no other effects changing your stats, maybe:
Hope this helps.