I feel like reddit has always had recurring and overlapping cycles of mean spiritedness. For instance, during the summer holiday period it becomes notoriously harder to have a reasonable exchange of ideas there (don't ask me why; I'm not quite sure). This year, since the beginning of the COVID19 isolation period in March, we've been in a period of very high mean spiritedness. It could be a consequence of users' high stress levels.
Reddit does still have several excellent communities. I find that there's one thing in common between them: They have real, dedicated, human moderators enforcing strict, rational policies. Also: There are some weird cliques of power moderators on reddit who control dozens if not hundreds of subreddits. A good subreddit is usually not run by those cliques. Not to discount the hard work that some grunt moderators put into trying to run the large, clique-controlled communities, but the commonalities are hard to ignore.
On upvotes: Reddit should have clear policies enforced equitatively and transparently at the company level, by a human staff, and downvotes shouldn't be presented as the opposite of an upvote. I don't see a complete alternative system that can replace the upvote, though. They do provide different sorting options; what else could they do, there?
On alternatives: People attempt to leave on a regular basis. The problem is that there's a much higher incentive for the people who are ostracized not only by reddit as a platform but by the associated community to leave than for people who are, for the most part, comfortable, even if the administration acts a little weird on occasion. All alternatives are quickly colonized by people that the majority of the reddit community (if there is such a thing) would rather not be immersed in: White supremacists, conspiracy theorists, fanatic nationalists, etc. For the more moderate people to be willing to move, they want to feel surrounded by a majority of people like them, not a minority.