Same here and also the back button does not work.
nostr:npub1gcxzte5zlkncx26j68ez60fzkvtkm9e0vrwdcvsjakxf9mu9qewqlfnj5z the indicator dot on my DMs won't go away even though I have o new DMs. #halp #asknostr
I'm on 70.5

Discussion
Back button? That's new. Any particular place?
The back button does not work in the sense that Instead of returning one step the whole app goes away. Here I opened it, navigated to this post and then press back once.
https://nostr.build/av/cfdb89a9471b462930a3080eaab8f1cb1002624c8abf1a31431bcf4102ba0880.mp4
Does it stay on after you Mark it all as Read? Sometimes very old messages arrive and they are all the way back in the list, but they are still unseen for that person.
Scrolling up and down helped, but sometimes the same message / notification appears after definitely checking it.
My dot fixed after I marked all read. I was having the back button issue yesterday, but I broke phone and had to get a new one and I haven't had the issue on the new one yet.
My old phone had multiple accounts, but I've only added the primary so far. I can add the second to see if it duplicates if that helps you out.