Despite MC-163400 being fixed and stopping parrots from imitating some neutral mobs, spiders/cave spiders are the only 2 neutral mobs that parrots can still imitate. The subtitle "Parrot hisses" can be seen if subtitles are enabled.
How to Reproduce
Spawn a parrot near a spider/cave spider
Enable subtitles
→ ❌ The subtitle "Parrot hisses" will appear
References
Comments 3
This is WAI, 99.99% sure. Look at MC-114933. They wouldn't fix that if parrots imitating spiders is a bug.
Not sure if it is WAI as spiders are neutral mobs, and parrots will only imitate hostile mobs.
Parrots are supposed to imitate the different mobs it's around