@Baraz The knocking down isn't 100%. Typically half of my party falls prone from the first jump. Unfortunately, I think you got super unlucky
Even if it did, this is addressed by spacing your party out. I'm fine with some encounters being incredibly lethal without foreknowledge. It's a game, so game-over then reload.
@Demoulius, I'm not Firesnakearies, but if the initial minotaur misses their attack then the rest is decently easy with some luck.
Use Fighter's Menacing Attacks that cause fear. If you use action surge and fear both minotaurs, that's a full turn where neither of them hit you.
Use hold person/web/other spells to restrain them
Use bane on them to reduce their likelihood of hitting.
Use potion of speed to increase your dps
Knocking down wasent 100% for me either. But if you did fall down the amount of incoming damage was pretty severe.
Menacing attacks is an interesting way to weaken them. Hadent considered that myself (mostly because Lae'zel wasent in my party at the time)
Hold person should not work on Minotaurs. They arent humanoid but large monstrocities. You would need hold monster, which is a 5th level spell. Web would work though. But only for a turn because you cant anchor the web between walls. (does it work like it does in pnp? Im not sure, havent tried the spell)
-Bane is a -D4 penaly to hit. If they have advantage chances that it wont do to much are fairly high.
-Using consambles can help at a pinch. Used a potions of strength and speed myself. But those give you bonuses, they dont make the minotaurs less nasty.
Anyway, whatever or not the player has good odds of fighting them (they are beatable, but it can be rough) isent the issue. To me anyway. More that these minotaurs arent minotaurs. And sure theyre allowed to homebrew here and there but.... every. single. fight. in the underdark is one such fight. At a certain point it isent fun anymore and the way that Larian amped up the difficulty is...lazy. All the monsters have been buffed in the same manner. They can all outright fly with how far they can jump, do aoe damage (which is the Bulette's signature move but ok), all have multi attack, all have some form of charge or sweep or BOTH. Basicly the only difference between these monsters is their HP bar and their 3D model. Because of this the fights arent interesting or memorable. Just hard. The difficulty also means that the underdark has only deadly encounters which any DM will tell you isent a good idea to put infront of your players.... unless you hate them with a burning passion I suppose.