Shoot, I should have read to the end. I searched PDF and a specific subcollection that had large PDFs, had to choose "includeP&C" to get anything to show up, selected all and trusted that even though everything was selected only the PDFs would go, and lost everything. I didn't see the warning about second conditions until too late.
But it's entirely my fault, and fortunately there were only about 30 items in the subcollection and I should be able to recreate it. Maybe the ability to filter by PDF size (either for searching above, or syncing below) would be helpful for some.
If you're saying you removed items from a collection by mistake, you should be able to easily restore from one of your last automatic backups. Follow the instructions for restoring a collection, which is basically the same thing.
Upgrade Storage
But it's entirely my fault, and fortunately there were only about 30 items in the subcollection and I should be able to recreate it. Maybe the ability to filter by PDF size (either for searching above, or syncing below) would be helpful for some.