This is absolutely not a new bug.
Combat Abilities Cancel Heavy Attacks
Heavy attack bug with Fury/Chastise ability
Pressing your ability hotkey resets your held heavy attack to light
FatShark gets a lot of flak for being kinda slow or for their…unique approach to certain issues, and sometimes it’s not completely justified.
But over the years there have been many such cases where they’ve reintroduced old bugs. This was also true with Vermintide 2 previously. Fatshark has an issue with version control, and quality control in general, and it’s nothing new to veterans of their Tide games.