Catch rates for max raid battles are weird. Serebii says that standard G-Max Pokemon have a guaranteed capture rate, but I honestly failed to capture g-max Centiskorch twice before I finally managed to nab it. It also mentions this though:
I'm not sure the validity of the claim that special event raids' capture rates are any different, especially since I've had problems with the aforementioned g-max Pokemon I mentioned. I think your best bet is to go for the Dusk Ball, as long as it's at night, of course. Thank goodness money is so easy to come by in these games, tbh.