The queen never paid for their clothes. TBH, I don't think any clothes are funded through the Sovereign Grant - other than staff uniforms. The Queen gave those who worked on her behalf, and didn't have an income stream, money from her own private account.
Prince Charles was totally responsible for funding William and Harry and their families. I guess W&H are funding themselves now.
I think those posts were about Harry saying his father refused to pay for Meghan. Cue the pile on over who had more spent on them clotheswise, Meghan or Kate. (Which I'm not getting into because I don't care. They both looked nice. ) I don't think it was about Charles being generous. Maybe others remember it differently, though.