I just updated my personal Mastodon server to the latest 4.3.4 version. It was a bit bumpier due to needing to upgrade some dependencies, but one major change for folks who modify the number of poll options, this is now handled inside app/validators/poll_options_validator.rb
More on my blog.
https://stefanbohacek.com/blog/how-to-increase-the-number-of-mastodon-poll-options/