Endless project loading. Plastic SCM login problem. (SOLOVED)

After porting a project from LTS version 2020.3.35f to the latest LTS version Unity 2021.3.3f1, it ran very slowly (sometimes compiling for 15 minutes), then stopped loading because of endless attempts to draw the editor interface. I'm not sure if I can enable profiling, because I can't objectively run the engine. Frankly, I'm confused. I'm attaching a screenshot of the rendering load.
Are there any options on how to fix this?
Or is it easier to go back to the old version of the engine?

 

I will try the options described here https://answers.unity.com/questions/1890967/help-unity-project-wont-open-stuck-on-projectbrows.html and report back

 

I went into the Plasic SCM app and logged into it via Unity ID and the problem really went away.