Portu devil state goes off while PvP or monster hunting

[JohnnyCash1]

Hi all,
When I play my Portu, especially in PvP, many times devil state goes off. I can't figure out why....is it some kind of bug? or is it by-design? and if it's not a bug, why does it happen?

Thanks

[Aky]

Can you upload video link of problem? Thank you!