Hiss / static / white noise when recording video or voice memos via microphone in lightening port

When recording video or voice memos with a headphone microphone attached (via aux adapter into lightening port, Apple brand) I get a really high level of hiss. I’ve tried a ton of fixes, including getting a brand new iPhone replacement this morning, and it happens on the new one! It’s an iPhone 11. Is this just how iPhones are? I know to expect some level of hiss with any recording. I tried the same mics with an android for comparison and the level of hiss was much lower. I don’t know how to film good content with audio this poor - is this some issue with all lightening ports trying to process audio?

Fixes I have tried:

• Getting a brand new phone replacement
• Brand new apple lightening/aux adapter replacement
• Three different headphone mics
• Using alternative camera apps
• Turning off stereo sound
• Updating to the latest system
• Restoring phone to factory settings
• Recording with wifi/Bluetooth/data turned off

Any help appreciated!