Hi, thanks for sharing this.
I strongly suspect that the code being run by these tests is modifying something in your foreground solution. Most probably there is an absolute file path somewhere. The consequence of this is that running the test causes the codebase (or a related resource) to change, which invalidates the results of the other tests.
If you move your solution to a different directory on disk, then try running the tests, does anything break?
There's a documentation page for troubleshooting this specific problem:
absolute file references