This actually happened to me, but fortunately I never actually used the domain. I registered tweed.dev intending to use robert.tweed.dev as a personal blog. It wasn't classed as a "premium" domain and the first year was £5 or something IIRC, which was half price compared to the normal renewal fee.
The next year they decided it was premium after all, and wanted to charge £492,000 for renewal. I still have a screenshot of that, although needless to say I don't own the domain anymore.
They operate the registry, but are not a registrar (bad choice of terminology) since they sold off that part of their business to Squarespace. Unclear to me who actually raised the price here since you can register a .dev domain with many registrars.
That's insane though, I assumed renewal prices were more or less locked in after you own a domain. Even the premium ones that go for thousands say they renew at the standard $12 or whatever.
The next year they decided it was premium after all, and wanted to charge £492,000 for renewal. I still have a screenshot of that, although needless to say I don't own the domain anymore.