When in a tmux session, panel dividers look a bit off/misaligned.

Can you post your tmux version and config? I'm using tmux in Hyper without problems.
I can confirm the same behaviour. It's not a tmux issue, I would say, since the very same configuration in iTerm2 doesn't have the issue.
All the lines that contain special glyphs need more room in hyper. Not sure why that is.
I'm using it with the Patched Nerd Fonts.
This is still a bug as of 25fcf3a6a4ec6abaeeaf17a1f6681e4c025483af on master

Hey there, please try again with the new Hyper v2 release and open a new issue if the problem stills exists. Thank you!
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I can confirm the same behaviour. It's not a tmux issue, I would say, since the very same configuration in iTerm2 doesn't have the issue.
All the lines that contain special glyphs need more room in hyper. Not sure why that is.
I'm using it with the Patched Nerd Fonts.