i found it's a BS excuse.
if you have guts to tell players frankly that you want to adjust or nerf the stats, players may complain but it's will be more understandable th*e 'bug' as the excuse.
if it's bug, we should hear it's bug like as soon after it come out. not like many moons later.

i found many times game developer use 'bug' as the classic excuse to be the way out to make more money.
nerf one thing , then make another thing for sale to replace the different.
it's a business i understand. but the way you approach it, it's terrible move.