Client 3.1.3
Ignored files: add enough information so that I don|t need to Google to figure out how to ignore / how subdirs are handled and whether “/” or “” is needed.
Even the NC Documentation is unclear.
In the end my .git folder is STILL getting synced 
For me the docs are correct. See Appendix B: History and Architecture — Nextcloud Client Manual 3.0 documentation
Ignoring files isn’t ignoring folder, right?
Have you read Ignore folder with Nextcloud sync on Windows and Ignoring a Directory ?
To ignore .git folder, you have to add .git/ to the list of ignored files.
If the folder is still synced, maybe it’s because of this issue in Nextcloud client. Try using the client version 3.0.3.
Or even better try Aaaand desktop client 3.2 RC3 is here! - #3 by eehmke to support the future.