Steps to reproduce

1. Create a flat survival world with commands enabled.
2. /effect @s resistance 9000 5 true
3. Let monsters hit you.
4. Equip some armor.
5. Let monsters hit you again.

Expected results

You do not take any damage because you have the Resistance VI effect.

Actual result

You take damage in step 5.

If you have resistance 5+ on you won't take any damage as intended as long as you don't have armor equipped.

However if you have armor on you will take damage.

Damage sources tested: lava, fall and mob damage. (Doesn't seem to effect fall damage.)

Does work as expected on java 1.16.

Might be related to MCPE-82952