Ambient mob effects in Mob Effects screen still use gray background

In 1.21.130.26 Preview, the ambient mob effects icon now use the same background as the one present in Java Edition, but this seems to only apply to in-game HUD, as the one in the Mob Effects screen still use the gray background.

Steps to reproduce:

1. Tame a Nautilus and then ride it

2. Look at the upper right of your screen, notice that the effect icon use the new background

3. Open Mobs effects screen (by pressing Z), notice that the effect icon still use the gray background

Expected results:
Ambient mob effects in Mob Effects screen use the new background, matching with the in-game HUD appearance.

Observed results:
Ambient mob effects in Mob Effects screen still use the gray background.