Yes, I understand the frustration. The team didn't come up with anything better although maybe they could. I think another suggestion in this thread could very well be posted to GIMP's issue tracker.
Looks like they created a separate gimp-ux repository a few mos ago at least. I'd gladly contribute design work and code there if my experiences would be more collaborative and less painful than they were before I just gave up trying like a decade ago. In my experience, anyone making a design contribution could only do it in a discrete standalone PR-- with gimp's foundational lack of UI design, that's like someone that owns a crumbling dam saying they will only accept proposals to fix individual broken spots because the pieces that are still intact work just fine. The only real options were to make a fork and change it, or... go fork yourself-- and there was no way I was taking on all of that design and coding myself.
Yeah, but trying to contribute design work to FOSS projects sucks— firstly, a whole lot of project maintainers think that UX and UI design hurt usability because they “dumb things down” to make them look pretty. Secondly, the workflows for code and design are completely different — you just can’t break design work down into a long series of modular pull requests like you can with code. I’ve encountered very few maintainers that don’t see that as a fundamental shortcoming of design and designers rather than a plug that needs a different adapter. Either way, you do a ton of upfront work for people that are suspicious of your motives and assume you’re incompetent, and it will either get totally ignored, or rejected out of hand. I’ve contributed somewhere on the order of 5 figures in coding hours to various FOSS projects and have a degree in design, and I still only contribute pure code features to FOSS projects.
I’m quite pleased to see that Gimp has undertaken this commendable step.