If it prevents the extension from working as described, it will almost certainly be an issue. If it does not impact the extension, it is potentially not a problem, but there are a large number of variables that go into it so it is very hard to say with what you have shared.
The specific CSP errors that are listed in that issue are about firebase attempting to inject dom elements to fetch remote scripts. That is not allowed with manifest v3. You would need to bundle the firebase files with your extension, and do something like rewrite the library code at build time to import the local files rather than the remote version. If you share a repo or build showing CSP errors, id be happy to help further.
patrick