Steps to reproduce the issue
Open minecraft
Then press play, and select a world
Wait to be fully loaded,
when enter in the world, connect another controller to the same console where you are playing
Then select a user connected to microsoft account
Next, then one player open the inventory
Observe
Expected result
The crosshair should not flickering too much should be static
Actual result
The crosshair will flickering when a player open the inventory.
Note: With this associated issue there is sometimes when enters in the world will encounter this crooshair flickering occurs sometimes.
This issue is being tracked at MCPE-123918.