OP seems quite knowledgeable (e.g. https://ogirardot.writizzy.blog/p/rickub-1-8-faster-then-git...), and their company ARUKU has been established in 2011, which makes me a bit more confident in this platform. But there are no details about the team, the software, since how much time they're working on it, etc.

At the same time, if you just use public repositories and synchronize them somewhere else for backup, there's not much risk in testing it. There's a free tier, they do have some neat features (that they don't really advertise) if you come from GitHub, like an import process that can copy PRs and issues or good compatibility with Actions.

The UI definitely needs a bit of love. While it's quite similar to other forges (you're not lost in the interface), it feels a bit rough. And the scrollbar presence or absence pushing the whole page left or right really bothers me.