Why has a grey border appeared around my Mushroom Chip cards?

Hello!

Does anyone know why these border boxes appeared around my mushroom chip cards (screenshot attached), and how I can remove them? I haven’t changed anything about these cards.

I’m not sure exactly which update this behaviour started with.

Thank you!

It is a general update of the GUI elements tht happend in one of the latest HA core updates.
card_mod can remove them, but I do not know how that work in tandem with mushroom.

Install Mushroom Shadow theme to remove them.