Did they change something about HE?

A few months ago I got overpressured in my Maus by a HEAT-FS shell from the M46.

I looked at the armor on the Maus and saw that there is a 10 mm plate there, and the HEAT-FS from the M46 has 13 mm high explosive fragmentation.

I also tested it with other HE shells and I was able to overpressure the Maus with them as well.

HE shells with around 600 g TNT equivalent can overpressure it from the front and from the back.

I managed to kill the Maus with HE using vehicles like the BT-7A (F-32), M8 HMC, and M8A1 HMC.

Until one or two years ago this wasn’t possible at all, but now it somehow is. That’s why I’m wondering if it’s a bug or if HE got a new function, because HE can now overpressure slightly more armor than its high explosive fragmentation penetration value suggests.

Test Maus vs T-34 or 122 mm gun vs Tiger II.

Are all of these bugs or intended by the developers, considering it has been like this in the game for months?