I'll second all of these, especially the lack of scrollbar and "expand text post in feed" button, and the hidden like/dislike buttons. The like/dislike vs upvote/downvote thing is tricky; I don't have a good solution for it, but maybe different icons that don't read as up/down would work.

Also, from a quick poke at things:

• There doesn't seem to be a way to switch the "For You" feed away from card view. I think it's fine if you want to make it a separate view setting from the main page, but I'd like to be able to change it to my view of choice.
• I'd like to see the post/comment body text tweaked for better readability: higher contrast against the background, a touch more space between lines, and a lighter weight (regular or medium) would all make reading long posts more pleasant, imo.
• In compact view, if I expand the attached image, there doesn't seem to be a way to shrink it back down, as clicking again opens the post.
• When viewing a post, there's a community sidebar on the right with all the rules and such, but that info is missing from the actual community detail page.
• The community sidebar on the post page scrolls separately from the rest of the post, which is weird to me on desktop. Giving it an "expand" button might be a good compromise, so you don't have the weird case of short post/long sidebar unless the user explicitly asks for it.
• Navigating front page > post page > community detail page, and then hitting back on the browser twice returns me to what the nav bar tells me is the front page, but only that one community's posts are shown. Refreshing or clicking "front page" fixes this, but it's a little confusing the first time.
• Navigating front page > community detail page doesn't trigger a... page load, I guess? My browser (firefox) doesn't recognize the community detail page as a separate page, so I can't hit back to go back to the main feed. Instead, I have to either refresh or click "front page".

Overall, though, this is super impressive!