The baseFee setting authority (Optimism SystemConfig which lives on Ethereum Mainnet) was transferred to a 6/8 multisig 0x9Eb44Da23433b5cAA1c87e35594D15FcEb08D34d managed by the Celo Core Co. team in this proposal: CELOccelerate: Celo Tokenomics Proposal.
This tx set the baseFee to 100 gwei so that is now the Celo minimum baseFee.