Hello,
Yes, you will need to protect your personal tags. You can create a main tag and place all your other tags inside it. That way, if you protect the main tag, all its subtags will also be protected. You can find a tutorial on how to do that here: How to Protect Personal Tags from being Overwritten
To undo the deletion, you can try restoring your collection from a backup. Please restore from a backup created before this incident occurred, and then protect the tags before updating the deck again. Here’s a guide on how to restore from a backup: How to Restore from Backup
Let me know if you need help with anything else. 