How can I locate photos that will be removed by syncing?

You probably don't need to worry about the Finder reference. Both Macs and PCs used to use iTunes for this sort of sync, and they probably didn't keep track of what system type sent the items. Now Macs use Finder, and Windows has some other followup sync program. Whoever coded the message you showed must have used "Finder" as shorthand for the three possible sources.

Photos and videos synced by iTunes/Finder from a Mac would appear under a Folder named "From My Mac" or something similar. (Some users quote slight paraphrases, so it may vary by iPadOS release or country.) Do you have anything like that on your iPad?

Involute wrote:

Yeah, there's a From My Mac folder in Photos that has 175 photos in it, and a matching folder on my Windows machine. So, the files are backed up. Thanks markwmsn and MrHoffman for pointing me in the right direction.

How can I get that folder back over to the iPad once it gets deleted? I assume the photos will come over via the iCloud sync, but they'll probably just be dumped into the library; I'd like to not have to pick them out individually to put in an album. I don't remember how I got it there in the first place.

First, view them and see if you even want to keep them.

Then copy the photos elsewhere.

175 photos isn’t all that many, having met various photo libraries with ten thousand and more photos.

Drop them all into an album named Sort Me Later, if you want.

And they may be duplicates.

It has been so long since I had a From My Mac folder that I don’t recall whether you can even put photos from there into a normal album. (Those photos are not really “owned” by Photos or part of its library.)

Do you know, MrHoffman? Will adding those photos to a normal album generate copies in the library or links to the “blob” of FMM items?

Involute wrote: … How can I get that folder back over to the iPad once it gets deleted?

The 175 "not owned by Photos" pictures will need to be added to Photos after you connect to iCloud. Probably the easiest way to do that would be to use the computer to go to iCloud.com, and upload them to iCloud Photos there.

I forgot that you are in iPadOS 17, rather than the newest OS 18. For you, all the iCloud settings are in Settings under your account ID. Photos settings are at Settings>Photos. Unfortunately, I've forgotten the exact details, and I can't look at my iPad, since it has iOS 18.

In iPadOS 17 the item counts and the status line were at the bottom of the library item array. Whether you will find an indication of an intentional pause and an option to resume, I could not say, but you might, or you might find another explanation for a stall in synchronization.

But that won’t help until you enable ICloud Photos, and the 175 photos will be gone by then.

Do you have 175 photos in your Windows iTunes photo library?

Sync photos in iTunes on PC with devices - Apple Support

I would make a backup of the photos.

If the photos get deleted, and if the photos are ones I care about, I can reload the copies.

In iOS or iPadOS: