CSS class selector not found - how to get rid of the error?

Question

Bootstrap

I downloaded the bootstrap project and then the same problem appeared on all existing projects at once.
VS Code throws an error on selectors - CSS class selector not foundand almost everywhere classes are underlined -

How to get rid of this problem? So far, one thing is clear, that this is due to bootstrap.

I found several solutions on the Internet, but they did not help me -