Currently our rounds are a minimum of 150 inputs, maximum of 400 inputs. There are usually a little more outputs than inputs.
The Bitcoin Core transaction standarness mempool policy is limited to 400kWU or 100kB, which means roughly 600 inputs, 600 outputs.
If the coinjoin is even larger, then default Core nodes won't relay the transaction to others, but we could send to miner pool nodes directly.
