Google is paying Mozilla to keep their search engine the default in Firefox. Period. There is no Google spyware (or any spyware in general) in Firefox. Just because Google is the default search engine in Firefox doesn’t mean Firefox is Google-controlled spyware.
Also Librewolf’s privacy is in some ways selfish on their part. It strips out Firefox’s troubleshooting data collection so Mozilla loses a good chunk of clues on how well the browser works. Lack of any data would lead to lower browser quality, ends up as a worse Firefox release, and Librewolf gets to be affected directly as a downstream of Firefox. By removing troubleshooting or usage data (which practically doesn’t affect privacy in any way), Librewolf is just hurting itself in the long run. If they’re really aggressive against directly contributing data back to Mozilla, then they should just run their own collection server and contribute the final data back to Mozilla.