WebM support

I have Big Sur 11.4.

I know that according to Apple Insider as of February 2021 they mentioned WebM is coming to Macs finally 11 years after it's launch... I was happy to hear that...

and even https://webm.html5.org ... tells me today with 11.4 my browser supports WebM...

OK... Macs are supposed to support WebM format now... but..

I have many WebM files on my computer and they only open in Chrome, Firefox or Opera.

I cannot open them with Safari. It's greyed out and dragging and dropping into a browser window shows a video file marked off and won't play.

Also WebP files don't work well in Safari. They play very poorly.

So... What is actually going on?

I have a website with WebM and WebP files and i'd like to host only one version of a file for everyone but due to the codec wars I host 3 different versions of each video for:

New Macs, 4k HEVC

Old Macs, 1080 HEVC

And PC or Non-Safari Computers. 4k VP9 (They don't support HEVC)

My 2015 Mac still won't play a 4k video even in Big Sur 11.4. But an iPhone 8 will... iOS 13 or so.

So a simple solution would have been everybody just use VP9 and WebM but... it seems that didn't happen... or if it did... I dunno why I can't.

So I just wanna know if Mac is really supporting WebM or not.

thanx