My only recent experience of Shimano brakes is Deore m535’s which I bought new / old stock for a good price for a cheap hardtail.
I don’t think they were meant to be some of the problem brakes (like the m8000 xts) but they’re not good at all. They squeal for the first few brakes and seem to need to warm up a bit before getting any bite.
Ive just replaced them with some second hand guide r’s and they’re so much better (using the same Shimano rotors). Got the same brakes on my enduro bike (200/180mm centreline rotors) and they just stop well with decent modulation.
I’ve had a go on a couple of bikes with Shimano brakes (1x SLX and 1 x XT) and was underwhelmed. The SLX bit too close to the bar from me and came on really strong all of a sudden. The XT bit in a better place, but still it came on too strong for my liking.