Canyon Mapping Boss root or stun bug?

I hope this is in the correct forum, i am not used to using forums for such things like this but i really can't understand it.

With unwaring stance, to not be able to evade attacks but not get stunned onto a build with cyclone against the two bosses in the map: Caynon. The dog boss looks good but the bird " roots " or " stuns " you.
I can see an arrow under my character's feet that immobilizes me, is this some different attack that i am not aware off or is this supposed to be a stun cause i literally cannot do anything during this time.

Thank you, GGG Community.

Its the bird :)

Its using vaal rain of arrows
https://pathofexile.gamepedia.com/Vaal_Rain_of_Arrows

"

Bear Trap and Vaal Rain of Arrows now remove all movement speed, as opposed to reducing it by 300%.

This change was introduced with 3.1 patch


So if that bird hits you with its rain of arrows, you cannot move as a result.
Bear trap doest the same and bear trap can be negated with a warding flask (curse removal). Might work for rain of arrows too - never tested it.

Rain of arrows (not Vaal version) can only stun not immobilize.