I have seeing this since the 1.16.0.64 release and when i type in command like:
/summon zombified_piglin it says invalid command syntax there is no wrong with the commands i have to type /summon zombie_pigman instead of zombified_piglin also when i type /summon piglin it do the same but instead i have to write minecraft:piglin,hoglin,piglin_brute,zoglin for a command to function well:

Invalid/summon piglin ~ ~ ~

Valid/summon minecraft:piglin

Valid/summon zombie_pigman

Invalid/summon zombified_piglin

Note: All mobs can be summoned without typing minecraft: except nether update mobs thats exception to the zombifiedpiglins