Its probably just MOD cope, but I do remember a lot of mechanical stuff under load having issues due to the thinner air and wild temperature swings. Some wrenchhead was saying how the outside conditions and air fucked with the oil/lubricants and made them less effective - I trust the guy with the most experience actually working on engines, but he might have been shouting at gremlins.
As others have covered:
It may be adding significant weight for not much effect. Explosives - shaped explosives but still - are glued to your armor. Additionally depending on the round and the ERA it might not make any difference when you are hit, as well as potentially making a small caliber hit more damaging.
The Germans are losing their shit "look at how they massacred my boy" style because this is sending their export weapon to the front looking like a mad-max hoopty wagon. They are also expecting Slav Engineering quality - Leopard 2 doing shit because of Slavs Slavving it up.
I believe they made some ERA bolt-ons for the Leopard 2 to cover the sides/magazine.
I mean have you not seen those huge gains around bahkmut after a year? Two more weeks guys, and then the Vatniks are going to be insufferable.