I now find myself using Photopea more than GIMP. Photopea is a browser-based photoshop clone. From what I understand it was built by just one guy, and it is in some ways better than GIMP. Pretty amazing work.
We all assume there's a vast army of dedicated people behind these things. Most people do just a tiny bit and don't stick around.
The reality is the core ranks are thin and the troops are exhausted. If you've got the time, they could use a hand (this is for all open source projects)
They people behind them are also usually effectively invisible when compared to the effort they put in so if you're thin on time, hunting down an email to send a sincere personal thank you would really make their day.
Just another lame example of how GitHub both (a) insists upon itself and (b) prioritizes its social network over providing actually useful tooling for getting work done (including but not limited to trying to glean insights about a given project).
GitHub only shows people with an email address linked to a GitHub account in that chart; the last time I checked it was 4 or 5 people working on it regularly, which is still a very small team (none are working on it full-time) so your point still stands (it's a point I've made myself a few times before when people compare GIMP to Photoshop or the like).
The GitLab chart[1] also doesn't seem to be accurate; e.g. Mitch only has 986 commits on that one (and almost 14k on the GitHub chart).
One example to test this: create a new layer, select a rectangular area, fill it with the paint bucket tool. Then use free transform to rotate that rectangle 45 degrees. The edges will be a mess. Its even worse at other angles.
I don’t want to slander Photopea because as I said I use it a lot, but I’d suggest to spend a while with it before deciding that you’re ready to ditch Photoshop/GIMP/Affinity.
I just gave it a try and I could load the image, edit it in various ways, and save it just fine. If there are any features that require being online, I didn't find them.