It's a small thing, but I think the heart icons for the like button should be swapped. To me, the heart outline currently used to indicate that you have liked a post has the appearance of being "unselected":
liked.PNG (Size: 915 bytes / Downloads: 312) (liked)

whereas the filled-in heart being used for un-liked posts is the icon that I would expect a liked post to have:
unliked.PNG (Size: 693 bytes / Downloads: 312) (not liked)

This has actually crossed my mind too @"TortelliniGenie" -- I'll likely rework the icon and appearance of that element altogether. Right now my focus is on a dark mode (and actually making the PM section mobile responsive), but this is a good reminder for sure.

Agreed!

Also kind of related: rather than showing every single user who liked a post, can that section just show a total number, or the way Instagram does it with "liked by [username] and X others"?

This is definitely part of what's planned @hadeg -- most likely, only the like box will be displayed and users will have the option to show everyone who liked it upon clicking +. That, or the box below will be limited to two lines and expandable.

I'm circling back to this now and will probably start by truncating likes (expandable) on mobile as a first step.

To piggyback off of this, is it possible to give individual posts a like or dislike? Similar to the star system in the top, but instead of the entire thread, just a particular post

(January 29, 2021, 7:34 am)BigBellyHunter To piggyback off of this, is it possible to give individual posts a like or dislike? Similar to the star system in the top, but instead of the entire thread, just a particular post

That's what this thread is about -- giving individual posts a Like, and how the icon for doing so seems inverted.