A commander that can bring out this much chaos by their turn four, my turn three, cannot be allowed to remain in the brawl format. By the time this screenshot was taken, the other player had 23 green mana he could have produced by turn 4. Unless I run a pure removal deck, what am I supposed to do about this sort of opponent. This commander shows up in many matches, and it ruins the competitive nature of a match.
Nyxbloom Ancient
Vorinclex, Voice of hunger
Ulamog, the Infinite Gyre
Emrakul, the Aeons Torn.

Player was only able to achieve this through Last March of the Ents, but the fact that this commander pops off this hard even "rarely" (it's easier to do than one might think) means your matchmaking is garbage. Remove this commander, and implement some sort of deckbuilding limits or matchmaking that looks at the entirety of a deck.