How is setting vsync different with SetHint different from the create window parameter? I don’t understand these “HINTs” …

I’ve never understood why there’s a vsync hint when we have SDL_RENDERER_PRESENTVSYNC. There’s usually an obscure reason for it. The other hints make a lot more sense though.

hints can also be set as environment variables at runtime (by the user), like
So a user can enforce vsync even if the developer didn’t set the flag in SDL_CreateRenderer() (for whatever reason), useful to keep your GPU cooler/more quiet or enhance battery runtime on laptops

Co się stanie, jeśli deweloper ustawi to jako WSKAZÓWKA?

According to the documentation an environment variable takes precedence. The implication is that SDL_SetHintWithPriority() can override an environment variable, although the documentation could be clearer on that point in my opinion.