Topics is rebranded FLOC. Everyone pushed back on it when FLOC came out, but that was publicly reviled and there was a simple toggle to turn it off (it was an experimental feature).
This is an excellent test of Google's ability to just push a very unpopular feature into Chromium derivatives.
> Non google browsers didn't only disable it, they removed it completely.
They set the toggle to false and deactivated any of the options to turn it back on. That's very different from removing a feature (or maintaining a legacy feature).
The only code they changed was UX-related and a single default.
And we still have to see if other browsers will block the Topics API spyware or not.