You'd probably have to look into whether TLDs count toward copyright, e.g. if company ABCXYZ (TM) could claim against abc.xyz.

The reallllly important thing is that you're not calling your chat app TinyChat, but Tiny. If you are calling it TinyChat and started after they opened, you'love need to reassess. If you're calling it Tiny, then you're better off.

Not a lawyer, just what I've experienced the laws around this to be.