Sort:  

You can find the version which each witness is running at:

https://steemian.info/witnesses

If they are showing to be running version 2.22 then it can be assumed they support it.

Thanks for the link!

It looks like for now in the top 20 only @timcliff hasn't upgraded yet.

Among the witnesses with a lower rank (from 21 to 40) the following ones are still running an old version (22.1 or even 22.0):