The usual remedy is to rebuild that Mac's Spotlight index. Instructions: Rebuild the Spotlight index on your Mac - Apple Support
Ironically the Finder has never really been very good at finding things. If you still encounter trouble there are a couple App Store apps I can recommend: EasyFind and Find Any File.
I believe EasyFind used to be on the Mac App Store, but I can no longer find it.
Developer's website:
https://www.devontechnologies.com/apps/freeware
Find Any File on the Mac App Store:
https://apps.apple.com/us/app/find-any-file-faf/id402569179?mt=12
I do not have any experience with any other similarly categorized apps, so please circumspect regarding anything with similar-sounding names. They will not be related to either of them.