My general rule is to be OK with any singular thing I use failing. This can be a hard drive or a company's sync product - mistakes happen even at companies. To do this I ensure for anything I care about, there are at least 2 copies that no single "thing" can touch both of.
So if some of your git repos are only hosted by a company and you have no local clones, that's a bad position to be in if the company terminates your account for whatever reason they might decide. But if you have local clones, it's fine. An ansible script can easily cover this (clone every repo you have).
If there are some files only in Dropbox, and you only have 1 computer sync'ing with Dropbox at a given time, all it takes is for Dropbox to screw something up and those files are gone. I wouldn't personally be OK with this. You might not care that much about what's in Dropbox though.
Beyond that, there are some files I don't want any service to have unless they are encrypted locally first. So I don't use Dropbox for that. Anything like that I keep in my regular documents folder. But those are mostly for my main "personal" PC, and don't need to sync those to things like laptops.
Note that recovering files in syncing services tends to have a limited time. So hopefully you notice before that time runs out. I have a friend that lost his military service documents while still using a file syncing service. We assume he accidentally deleted them years ago. Couldn't recover it.