This bug is on version Combat Test 8c, however there is no version option for this.

Small graphical glitch that occurs when toggle sneak is enabled and shield is being held up and upon death the client screen shows shield being held when it is down.

Steps to reproduce:
Use version CT 8c (from Reddit preview)
Load into multiplayer LAN world.
Set 'gamerule KeepInventory true'.
(P1) Enable toggle sneak and start sneaking.
(P2) Kill P1 with axe.
(P1) Press 'Respawn'.
P1's screen will show a raised shield, indicating damage to be blocked when in reality players connected to server see a lowered shield and can inflict damage as usual.