This bug ticket is a parity issue, since Java 1.16.2 pre1 has already this feature.
Step to Reproduce:
Spawn some striders until you get zombified piglin riding one.
--> ❌ They don't spawn with warped fungus on a stick on their hand.
MCPE-94002
Parity: Zombified Piglin riding strider don't spawn with Warped Fungus on a stick on their hand
Resolved
Fixed
8
(Unassigned)
389100
Confirmed
Multiple
vanilla-parity
1.16.100.52 Beta, 1.16.100.51 Beta, 1.16.100.50 Beta, 1.16.20.54 Beta, 1.16.1, 1.16.10, 1.16.20
1.16.100.54 Beta, 1.16.100
Retrieved
A new beta didn't came out this week yet. So, it's obvious they don't spawn with warped fungus on a stick.
It would be better to wait for the new beta to come out before you report the bug.