I read something that Bambu is no longer being open source and restricting something? Does that change anything if it’s still worth getting?

It's more along the lines of Bambi restricting access and features via APIs for those controlling a print farm. For a single user I think it wouldn't be a big issue.

just bought a bambu printer. what brand of filament does everyone use and which place is best bang for buck to buy at?

I bought a bunch of Bambu Lab filaments and most were fine. Some came loose and were a PITA to respool though. Going through their support was worse than useless - the snarky lady on the other end basically accused me of lying.

On a similar note, anyone here interested in buying a lightly used A1 Mini? I used it a few times only and don't really want it around anymore. DM me if interested.