casino says side bets made my blackjack bonus ineligible after they already accepted them

I finished a blackjack bonus last week, played mostly standard hands but threw in some side bets for fun. Now after everything went through, support told me those side bets voided my bonus, even though the system took my wagers and gave me bonus progress the whole time. Feels kind of shady to tell me after the fact instead of blocking or warning me up front.

Anybody else have casinos pull this on them before? Curious if I’ve got any ground to push back, or if this is just how they get you.