I just tested it again. It's indeed caused by a card effect. All the card effects reduce my speed. Is it normal or a bug? This happens every time when I do my daily hp quest.
Not bug Every card different effects Even u have full set Loot card still get buff That’s why ppl do Nt boss after get auf card first
The Birk card effect expires in the area where you went I think, so the effect from your looted card(s) goes away, and you just have to re-haste yourself since this is a game mechanic and I don't think it's a bug