Looks like it is a issue with the CSS
style sheets ? Whenever I have upgraded, I first 'purge all caches' and again purge after the new version is installed.
You can also try switching to a different there for a few minutes and check if things look normal; and then switch back to your preferred theme. It will confirm if the issue is with the theme files.
Try using a 'safe' default theme like Boost, without any mods and see if things get better.
About the re-installation:
I am not sure if the re-installation is a good idea, unless you have rolled back the database
also to the pre-upgrade status.
Since I use a cloud server
, I find that taking a snapshot just before the upgrade helps to vert to the previous state if things don't pan out well.