Looked at it once. If you disable telemetry in VS Code, it is pretty quiet (depending on whatever extensions you have installed) with regards to network traffic. Hence I do not really saw a need to continue with VSCodium.
But it might be a good thing that it is there, so it keeps VS Code (more) honest. VS Code is a Microsoft product after all and they are allowed to (and did so in the past) change licensing of their products. Perhaps I should take a look at VS Codium again myself, it has been over a year since I last checked. Things might already have changed.