And how does one become a maintainer, if there's no way to contribute from outside? Even if there's some extensive "application process", what is the motivation for a relatively new user to go through that, and how do they prove themselves worthy without something very much like a PR process? Are we going to just replace PRs with a maze of countless project forks, and you think that will somehow be better, for either users or developers?
If I wanted to put up with software where every time I encounter a bug, I either have no way at all to report it, or perhaps a "reporting" channel but little likelihood of convincing the developers that this thing that matters to me is worthy of attention among all of their competing priorities, then I might as well just use Microsoft products. And frankly, I'd rather run my genitals though an electric cheese grater.
You get in contact with the current maintainers and talk to them. Real human communication is the only shibboleth that will survive the AI winter. Those soft skills muscles are about to get a workout. Tell them about what you use the software for and what kinds of improvements you want to make and how involved you'd like your role to be. Then you'll either be invited to open PRs as a well-known contributor or become a candidate for maintainership.
Github issues/prs are effectively a public forum for a software project where the maintainers play moderator and that forum is now overrun with trolls and bots filling it with spam. Closing up that means of contributing is going to be the rational response for a lot of projects. Even more will be shunted to semi-private communities like Discord/Matrix/IRC/Email lists.
If I wanted to put up with software where every time I encounter a bug, I either have no way at all to report it, or perhaps a "reporting" channel but little likelihood of convincing the developers that this thing that matters to me is worthy of attention among all of their competing priorities, then I might as well just use Microsoft products. And frankly, I'd rather run my genitals though an electric cheese grater.