Who Typically Sets the Minimum Transaction Fee in a Decentralized Network?

The minimum transaction fee is not typically set by a single authority in a decentralized network. Instead, it is determined by a combination of factors.

The protocol itself may have a minimum fee for a transaction to be considered valid. More commonly, individual node operators and miners set a minimum relay fee as a policy for transactions they will accept into their mempool and broadcast.

The effective minimum fee is ultimately determined by the competitive fee market, where the lowest confirmed fee is set by the collective behavior of profit-maximizing miners.