Hello
I tried to buy stars by credit card.
It didn't work.
Is this a bug or is the functionality no longer usable?

Are you trying to do it on mobile or PC?
Apparently it didn't work on the former: #forum?topic=166679

Yes I was on mobile
I'll try on PC
And I will put here the result

I confirm
Buying stars on a PC via credit card works.

On the application it does not seem to be the case