PDF cropping in Preview

I understand that cropping (cmd K) doesn't actually crop the image, it just hides the bit outside your selection (a bit pointless, if you ask me). But I have discovered another annoying thing, when cropping multiple pages of a PDF document, after I make a selection on one of the pages, (using the rectangular selection tool) another cropping box appears on a page further up the column. On a couple of occasions, when I've scrolled back up the pages, one or other of the previous crops, have jumped out of place, causing parts of the document to be chopped off. There didn't seem to be any way of rectifying this other than multiple cmd Zs, which only resulted in much wasted time and a lot of frustration. Why can't Apple just give us a proper cropping tool? Is it THAT difficult?

And before anyone asks, I'm using a 2020 iMac 27", with 16GB RAM and Sonoma 14.2.1, Preview version 11.