sending transaction without gasfee or gas estimate

[mattador1]

Hi, if I send a transaction through ethers without using gasEstimate (not setting gasLimit) and also not setting maxFeePerGas and maxPriorityFeePerGas, what happens when I broadcast this transaction?

does ethers under the hood contacts provider for those estimates and use them, cause I know you can call provider.getFeeData or do a gasEstimate manually prior to calling the method on contract.

What values are used ?