This does not protect the cards
To protect the cards, you will need to either protect that field or add one of the “AnkiHub_Protect::Text” or “AnkiHub_Protect::All” tags
This is why your cards have stuff getting removed. This post will explain everything you need to know about protecting: 🔐 Protecting Fields and Tags
Adding %%keep%% to the protected tags will only keep that tag from getting deleted, not the card