And since you won’t be able to modify web pages, it will also mean the end of customization, either for looks (ie. DarkReader, Stylus), conveniance (ie. Tampermonkey) or accessibility.
The community feedback is… interesting to say the least.
I used it up to the early 2000’s and it just seemed to slow down. I recently did a series of synthetic benchmarks on all the browsers and Firefox was the slowest of the batch. It’s still the only browser left not built on chromium I think. Opera GX was the fastest in terms of benchmarking.