[2021] Sneak attack mechanic not working after U29

I'm pretty sure something changed, I can't get this to 1-hit enemies reliably anymore.

Before if I was
- hidden
- doing a fully charged heavy attack
- while flanking
it would always
- perform the sneak attack bonus
- and make it a guaranteed crit
- AND stun the enemy.
This is in PvE.
It feels like the sneak attack bonus was sneakily nerfed, whether on purpose or by accident. From the dozen attempts I made, it feels like it only works with your actual critchance and is not a guaranteed crit anymore either. The stun and boosted damage are not even executed.

Question: Anyone else experiencing the same?
@ devs: Is this intended?