please note: for whatever reason, Apple removed the progress bar on copying files from/to iPhone.
therefore, you’ll have no idea how long copying takes place - until the destination file shows the correct file size - which may take tens of minutes if the file is some gigabyte large. please stand by and do not disconnect the iPhone until you see the correct file size - unfortunately, Apple also seems to have removed the warning when outplugging the phone, so “just” doing that will result in incomplete, corrupted backup.
(tested on ios 15.3, macos 12.3 - took me some time to realize the issue and that copying really takes so long)