I just got a Macbook Air 2020 running Big Sur. They did an update last night from 11.0 to 11.1. I am running an iPhone 5s 12.4.9.
I have never had an issue syncing my 5s with my MacBook Pro High Sierra which the MacBook Air replaces.
Today I plugged my phone in and I too have this annoying pop up but some of the guidance here does not jibe.
For instance Open Image Capture using the three dots beside the trash. What three dots? There aren't any so I went into Launch Pad opened it.
When I plugged in my phone I got The file cannot be found window which I cleared.
The phone showed up as locked so I clicked on it and up came my pictures on my phone.
I disconnected the phone, repeated the process and it came up the same.
The point is I don't want this to happen. If I plug into my MacBook Air then all I want it to do maybe to sync music or just simply charge while I work.
This falls under another of the geek mantras. We do stuff because we can, not because it adds value and to annoy the users we will make it a case they must figure out how to opt out.