I installed 9.3.3.0 this evening and haven't noticed any particular GUI changes from my settings for previous version. I am running Win10Pro 64bit if that's of any relevance.
Julian, if you should see this problem again, please make screenshots and send them to the developers using the Support menu above, along with any relevant details that you can think of (O/S, theme, etc).
I volunteer as a moderator to help keep the forum tidy. I do not work for Ritlabs SRL.