Google aren't pushing WebP. Google Docs / Slides still don't support it.
I appreciate Google isn't a monolith, but that lack of consistency makes it really hard to shake the impression certain tribes within it are at war with each other.
Strangely enough, Google wouldn't index my personal website when I was using webp. Everything in my Search Console showed up as "crawled but not indexed." I had multiple friends with SEO backgrounds check out my site, but everything looked configured correctly.
Switching all my images back to jpg solved it
This is actually a good counter argument for 'Google is pushing X'. If they were pushing X, they'd make all their apps fall in line.
Contrast this to, say, Apple - which when decides to push something, they go all in. And that's an example of top-down decision making.
It's not war, it's indifference. Why should Docs give a damn what Chrome's priorities are? The only reason they would is if there were effective leadership ensuring company-wide alignment, but there is no one filling that function.