Creeper explosion/Armour issue

This is my first bug-report so I'm not very familiar.

I'm playing for fun/relaxation on 1.16.4 Pre-2 and something weird occured to me (I haven't played vanilla minecraft since 2014, only modded, so I'm not sure if this should be correct or not). While I was mining a creeper fell next to me, I was wearing a full iron armour set, yet I got obliterated by the creeper without even surviving the explosion as if I was wearing no armour (it isn't as I remember it back when I played vanilla MC around 2014), so I went to test damage done to me based on how far away a creeper is on versions 1.16.4 Pre-2, 1.16.3 and 1.14.4, while wearing a full iron armour set.

Edit: All tests were done on normal difficulty, the creepers were not charged ones, tests were done on flatworld.

By my testing this is what I found:

Distance between me and creeper 0~1 blocks:
1.16.4 Pre-2: Instant death.
1.16.3: Instant death.
1.14.4: Survive with 2-3 hearts.

Distance of 2 blocks:
1.16.4 Pre-2: Instant death.
1.16.3: Survive on half a heart to one heart.
1.14.4: survive with 4-5 hearts.

Distance of 3 blocks:
1.16.4 Pre-2: Survive on 2-3 hearts.
1.16.3: Survive on 3-5 hearts.
1.14.4: Survive on 6-8 hearts.

By no means I did an extensive test of the explosion damage, and I am unaware if this is intended or not, the armour I had was not enchanted at all, I simply did some quick tests of the damages.