

stuck with the GPL forever
If you accept a patch and don’t have the ability to relicense it, you can remove it and re-license the new codebase. You can even re-implement changes made by the patch in many cases, whether those changes are bug fixes or new features.
If you re-implement the change, you do need to ensure this is done in a way that doesn’t cause it to become a derivative work, but it’s much easier if you have copyright to 99% of a work already and only need to re-implement 1% or so. If you’ve received substantial community contributions and the community is opposed to relicensing, it will be much harder to do so.
A clean room implementation - where the person rewriting the code doesn’t look at the original code, and is only given a description of the functionality - which can include a detailed description of the algorithm - is the most defensible way to perform such a rewrite and relicense, but it’s not the only option.
You should generally consult an attorney when relicensing and shouldn’t just do it casually. But a single patch certainly doesn’t mean you’re locked in forever.
If you dislike decentralization, then that’s like being on an instance that’s banned every other instance.
Do you mean that you dislike defederation?