When taking damage on java The Hearts flash for 1 second and it also shows you how much damage you just took. However on bedrock when you take damage the hearts will either flash for a splitsecond, or it will not flash at all, and it doesn't show you how much hearts you just took.
You can also slow down the video and you will notice the bug
Note I am using a A resource pack that makes the Minecraft Bedrock game look like java so please don't mistake it as the actual Minecraft Java
This java edition screenshot is actually a bedrock resource pack from MCPEDL.com made by Crisxolt that modifies the bedrock UI to make it like java but due to the create new world screen and death screen being hardcoded to use the new Ore UI engine it's impossible to change those screens. This Minecraft is Minecraft Bedrock Version Beta/Preview 1.20.80.23
This is actually for bedrock it's just a ui pack to make bedrock look like java.
This is not from marketplace.
I also forgot to mention that Hearts on java do flash when regenerating as well.