I see that people have mentioned this bug but I have just figured out how to reliably reproduce this. It's a very annoying bug because if you make a lot of changes you will lose all progress due to this bug.

Steps to reproduce:
1. Open any deck
2. Remove at least one card from the deck
3. Click on the deck name to open the Deck Details screen (the one that shows the mana curve, card stats, etc.)
4. Try to go back to the Deck Builder screen by tapping the back arrow button

Behavior:
1. It registers as you tapping the deck name button which opens up the keyboard to rename the deck
2. The back button is seemingly impossible to tap, I have tried tapping every where around it and it doesn't work

Notes:
- If you just add cards to the deck and don't remove any, this doesn't happen
- Opening and closing the app doesn't fix it
- You can only exit the Deck Details screen by clicking on any of the top sidebar buttons like Home or Achievements which prompts you to discard the changes and gives no option to save
- Doesn't happen on my Windows 10 PC

System details:
- On latest Arena app version as of writing this (12/02)
- iOS 26.1, iPhone 14 Pro