You marked my comment above as the “solution”. I would just like to clarify adding PythonCall didn’t do anything for you, or shouldn’t have, so I do not want to take credit for that.
Your rm PyCall did something, and even if you do not see it in with (@v1.7) pkg> st i.e. it no longer there in the Projects.toml file, it’s there in ~/.julia/environments/v1.7/Manifest.toml because PyPlot depends on it.
If you want to credit me with “fixing”, by accident, then rather point to this post to not confuse others.
EDIT: I wrote adding PythonCall didn’t do anything, but one possibility is it forced an upgrade for Conda.jl. It depends on version 1.5, while PyCall only depends on 1.0. I’m not sure what caused your fix but it’s a likely candidate, and looking at Conda I saw:
https://github.com/JuliaPy/Conda.jl/issues/138
If Conda had anything to do with this, you could have gotten the same effect by only upgrading it (and you should be able to rm PythonCall), and then maybe PyCall should add as strict a Conda requirement.