Steps to reproduce:

1. Drop a gunpowder item onto the ground
2. Run:

   /data modify entity @n[type=item] Tags append from entity @n[type=item] Item.id

   The server should return the message Modified entity data of Gunpowder

3. While near the same item, run:

   /tag @n[type=item] list

   The server should return The [X] entities have 1 total tags: minecraft:gunpowder

4. Run:

   /tag @e remove minecraft:gunpowder

   or

   /execute if entity @n[type=item,tag=minecraft:gunpowder] run say hi

Observed result:
The server returns

Expected whitespace to end one argument, but found trailing data
... minecraft:gunpowder<–[HERE]

or

Expected end of options
...=minecraft:gunpowder] run say hi<--[HERE]

Expected result:
The server returns

Removed tag 'minecraft:gunpwoder' from [X] entities