Separate colour schemes for separate accounts
If you were logged in to multiple Lemmy accounts on the app, you could easily tell which one is currently selected if they affected the colour scheme of the app.
Since themes is part of settings, it might be better to have separate settings for each account.
I know sync has that option.
There are already separate settings per account, but not themes. At least when I made changes in one account, like remove the tab bar, it did not take over to the second account I have in the app.