The Bug:

Hotbar selection resets to slot 0 upon death.

Steps to Reproduce:

• Give yourself two different items held in different hotbar slots.

• /item replace entity @s hotbar.0 with minecraft:dirt
  /item replace entity @s hotbar.1 with minecraft:deepslate

• Hold the deepslate in your hand and set the "keepInventory" gamerule to "true".

• /gamerule keepInventory true

• Run the "/kill" command.
• Take note as to whether or not hotbar selection resets to slot 0 upon death.

Observed Behavior:

Hotbar selection resets to slot 0 upon death.

Expected Behavior:

Hotbar selection would not reset to slot 0 upon death.