Power to the people! Yes, it sounds cheesy but this extension does it. Screw YouTube removing the dislike count, this gives us a replacement for it.

Update: The new permissions request in Sept 2026 has some terrible wording. This extension accesses the same websites as it did before - youtube.com and returnyoutubedislikeapi.com (see under "Permissions and data"). I was concerned by the "new permissions," since seemingly everything nowadays is grabbing as much of your data as possible. But since the extension runs on the same sites, it's open source, and the wording of these permissions is controlled by the platform (Firefox in this case) *not* the developer, I'll keep it.