photoanalysisd and photo

It you cannot eject a shared volume or if your shared volume is always mounted, perhaps it is based on photoanalysisd that analyzed your photos.
Check which software is using your disk with:
First, search for the name or your volumes using
ls /Volumes/
Then, look what software is using the volume MyDrive
sudo lsof /Volumes/myDrive

For what it's worth (and with all the usual disclaimers about potentially making your mac unstable by disabling system services), here's some commands that will manipulate this service and services like it. Note the $UID in the command, that's just a bash shell variable that will resolve to some number. That's your numeric UID. You just run these commands from a Terminal command line. No special privileges needed.
If you want to disable it entirely, the first command stops it from respawning, and the second kills the one that is currently running:

launchctl disable gui/$UID/com.apple.photoanalysisd
launchctl kill -TERM gui/$UID/com.apple.photoanalysisd
(If you kill it without disabling it will die, but a new one will respawn and pick up where the old one left off)
I don't have this problem myself, so I can't try these next two commands. They're relying on good ole UNIX signals. You could theoretically suspend and resume the process like this ("STOP" and "CONT" are stop and continue):
launchctl kill -STOP gui/$UID/com.apple.photoanalysisd
launchctl kill -CONT gui/$UID/com.apple.photoanalysisd

It seems that there is another process that do the same:

launchctl disable gui/$UID/com.apple.photolibraryd

launchctl kill -TERM gui/$UID/com.apple.photolibraryd

It does not work with macOS Catalina (: