This is how every new thing starts though. You don't just get better standards overnight. Jpg and png didn't happen overnight either. PNG had this problem for quite a while.
It's not a problem with WebP. It's a problem with tooling that aren't moving forwards to objectively more effective formats.
HEIC now has a licensing cost to it, meaning devs have to pay to make their software able to open it. Microsoft recently removed HEIC support from their software because of it.
Nope. JPEG XL is more modern and delivers lower file sizes without fucking up image quality as much. Downside is that, right now, JPEG XL is actually supported by even less things, because it is still so new.
But it is an industry standard rather than just Google trying to push its own thing, so I do expect it to overtake WebP in a few years.