3.0.0.8 doesn't work any longer.
On Linux (Firefox 102.10.0esr 64 bit on Debian 12 and Firefox 112.0.1 64 bit Snap on Ubuntu 22.04) there's no longer any effect visible. Both Firefox behave as if "Return YouTube Dislike" isn't active at all. The only "function" available are the settings, which can be changed - but with no effect.
You replied to another user ("3.0.0.9 is still in review by Mozilla, give it some time untill you see that 3.0.0.9 is available in addons store - it fixes all the issues").. . so I simply will wait. As mentioned: For 3.0.0.9 I'll rate it again.