It's a musical that was released day and date on HBO Max during the pandemic.

Yeah. Too bad. This would have been a splash.

I don't really know what a 'splash' is, but this was a movie musical, adapted from a stage musical that wasn't a big hit, and it starred nobody well known at the time. And it came out early enough in the Pandemic. I don't think it was ever going to make much money.
Honestly there isn't much of a market for movie musicals. The Color Purple (a much better known property, with some well known stars, opened decently with an $18M on Christmas, and then plummeted the very next day. It dropped 74% in its second week. These movies do not draw moviegoers, sadly. That's why Mean Girls is trying to keep it a secret that it's a musical :

Wonka did as well.

That’s not really new. Even Disney has disguised some of its musicals in the trailers, and a lot of their brand is based on musicals. I can understand trying to hide Mean Girls because people may not expect it from the original film, but yeah, I agree with the basic point that people hate musicals.

Wonka is doing pretty well right now.

It is. It's also based on a beloved property, stars a hugely famous and popular actor and the fact it's a musical is kept extremely well hidden.

It will be interesting to see how Wicked, an adaptation of the most popular Broadway musical of all time, is marketed.

Musicals generally sell better as family movies (Wonka, Frozen I/II, The Greatest Showman, Encanto (which got the raw end of the deal theatrically but has been a force on streaming))

it usually isn't seen as a big selling element though