I have never had trouble importing from iOS/iPadOS but below are some possible fixes that have been used:
- Put the phone in Airplane mode before plugging in the USB cable (maybe also turn off Bluetooth, Wi-Fi, Hotspot).
- Move ~/Library/Preferences/com.apple.imagecapture.plist to the Desktop, (just in case you need it later) reboot, and try again.
- Remove all 3rd party virus apps (Avast, AVG, Bitdefender, Intego, MacAfee, Norton, ESET NOD32, Trusteer etc) and 3rd party "cleaning", "optimizing", "speed-up" apps (CleanMyMac, MacKeeper etc). They produce only obscure errors and money loss.
- Reset iPhone's Network settings.
Change your settings for trusted computers. Settings > General > Transfer or Reset [Device] > Reset > Reset Location & Privacy.
About the 'Trust This Computer' alert message on your iPhone, iPad, or iPod touch - Apple Support
Clean the lightning/USB-C port from pocket lint.
Connect to the Mac's USB-A inputs, not Thunderbolt USB-C inputs.
Turn off iCloud Photos in iPhone settings.
Use AirDrop instead USB.