If you suddenly get thousands of TS related error messages in a Visual Studio project, in our case Visual Studio 2022, .Net core 6.0 (but I suspect the same in other versions) eg:
To fix this, there are a couple of solutions [although still cannot figure out if these are correct, but help] 1) Change the "shows Issues generated" dropdown to Build Only
2) and/or Change the project filters in the Error List window, by de-selecting specific apps/files.
Let us know if you find any more definitive solutions.. Hope this helps.