AMSupportURLConnectionDelegate and AMSSupportURLSession both multiply defined

When running various tools, such as "opendiff" I receive the following error:

objc[6599]: Class AMSupportURLConnectionDelegate is implemented in both /usr/lib/libauthinstall.dylib (0x1e30deb90) and /Library/Apple/System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x108f7c2c8). One of the two will be used. Which one is undefined.

objc[6599]: Class AMSupportURLSession is implemented in both /usr/lib/libauthinstall.dylib (0x1e30debe0) and /Library/Apple/System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice (0x108f7c318). One of the two will be used. Which one is undefined.

This appears to be related to the problems reported here: https://discussions.apple.com/thread/252824300

(Apple won't let me update that thread and is forcing me to make a new one -- what's up with that, Apple?)

This is probably caused by something installing a conflicting library -- in the above thread, various people are using homebrew, I am using MacPorts -- but the issue is the same.

What makes this VERY peculiar is that there is actually no file on my system with the name /usr/lib/libauthinstall.dylib so I cannot determine where this conflict is coming from.

I have an M1 mac.