Unity 2021 new project open with collab errors!

No surprise here, happens ALL the time.

Extra unwanted packages in new projects (collab, testing, rider and other junk):

About the fastest way I have found to make a project and avoid all this noise is to create the project, then as soon as you see the files appear, FORCE-STOP (hard-kill) Unity (with the Activity Manager or Task Manager), then go hand-edit the Packages/manifest.json file as outlined in the above post, then reopen Unity.