The _prepareBasicFulfillmentFromCalldata function prepares ABI encoded data at fixed location in memory (starting at 0x80 and writing as high as 0x1e0+0x20).
The overwritten memory does not seem to be saved, and this function has multiple assembly blocks (probably for avoiding stack too deep errors?). The only field restored is the zero slot.
The only use in Seaport is the Consideration.fulfillBasicOrder  _validateAndFulfillBasicOrder  _prepareBasicFulfillmentFromCalldata call chain, where this does not seem to be a problem, because they are not allocating memory prior to entering this function (according to displaying the free memory pointer in the test suite).
This would become a big issue if some functions would allocate memory. It is also very dependent on the compiler version.
Context: Consideration.sol#L76, BasicOrderFulfiller.sol#L70, BasicOrderFulfiller.sol#L325
Consider restoring the dirty memory.
