Seems wrong and not consistent with zombie villager conversion - either they should keep the armor or drop it.
The important difference to MC-172121 is that this report is about items picked up by the piglin, whereas MC-172121 is about the items it already had equipped when it spawned.
Piglin change to zombified Piglin，the armor continue to have
Piglins don't drop their inventories when converted to zombified piglins
Parity: Piglins and Piglin Brutes delete their armor while zombified
drowned dont drop items that they picked up as zombie then were converted
Piglins do not drop their gear when turned into a zombified piglin
Zombified Piglins don't drop their picked up inventories when killed