I created a survival world on version 19w35a on normal difficulty, in singleplayer, set "allow cheats: OFF"(which means I cannot switch between gamemodes), in this created world. Recently updated to 19w36a, and accidentally found that I take no damage from falling, I thought it was because of my iron boots (even it has no enchantment on it), after my boots were destroyed, I still take no damage at all no matter what height I am falling from. Another thing is I take no damage from suffocation in water, I tried to stay in water for a minute, the bubbles were long gone and I still take no damage.

I experienced fall damage early game, so I think it's from the new patch 19w35a, but I'm not sure if the patch is exactly the time when I start to take no damage from falling. However I never experience suffocating in water in version 19w35a, so I cannot tell if it's the patch 19w36a causes the issue that I take no damage from suffocate.

The first 2 screenshots are standing on level 143 before I jump, and land on level 69 after I jump.

The 3rd screenshot shows that in the UI, it exists that the bubbles showing how much longer before I suffocate, the 4th screenshot show that I take no damage even without the bubbles left.