Barriers appear gigantic when flying over them

This happens on an iPad 2018 with iOS Version 12.3.1. Does not happen on iPad 4 with iOS 10.3.3!

What I expected to happen was...:

Barriers appear as normal Blocks.

What actually happened was...:

Barriers appear gigantic when directly flying over them - on different heights.

Steps to Reproduce:

• create new world in creative mode
• /give @s barrier
• place barrier on the ground
• step on barrier
• fly up
• ... on some height (ranges from 1 to 100 with my tests) the barrier appears gigantic as seen on the screens attached:

What version of Minecraft are you running?

v1.12.0