There’s been a lot of discussion about the colour of the card (some like it, some don’t) here -
if you’re an iOS user, you can set the app to not display the number of unread notifications in Settings > Notifications > Monzo > Badge App Icon
You can report bugs through the support chat tool that’s built into the app, as well as in the community…maybe a form would make that process easier but I like the fact that you’ll currently get a human response straight away, when you submit it there.