This becomes dangerous with how-to videos which used to be easy to spot if they weren't very good or fake.
This extension is working well so far to display the likes and dislikes, but I don't know for how long...
https://returnyoutubedislike.com/
> A combination of archived data from before the offical YouTube dislike API shut down, and extrapolated extension user behavior.
How reliable is this?
Works fine for older videos where the like/dislike count was archived. On new videos, not that much, since it's dependent on data from other users also using the plugin.