I had previously bemoaned the fact that the proxy icon is now hidden behind a hover delay in Big Sur. In that post, I mentioned that you could remove that delay in Finder using the command
defaults write com.apple.Finder NSToolbarTitleViewRolloverDelay -float 0. But that only affects Finder, and you have to repeat it with various bundle identifiers for each app making use of the Big Sur toolbar layout.
I have since realized you can set this globally for all apps in one fell swoop:
defaults write -g NSToolbarTitleViewRolloverDelay -float 0
As far as I can tell, that seems to have done the trick. Just thought I’d update with the new info. I’ve updated the older post as well.