I just upgraded my laptop from MacOS High Sierra to MacOS Big Sur and noticed my Conda is missing including my environments.
I tried installed back Conda but the environments still not available.
Fortunately, the MacOS upgrade did not remove my environments but it just moved them to another location which located here.
And my current Conda folder is here.
So what I need to do is just copy the environments folder called envs to the current Conda folder.
PS: I believed the same method also works if you upgraded to MacOS Catalina.