I have also noticed that the ADF feeds crooked when scanning. But since I only use scans for archive purposes for invoices and receipts, it doesn't really matter to me and the few that have to be clean I put on the glass manually. But when I measured my last few scans with the ADF, I could already see up to 5 mm offsets at the top and bottom, which is quite crooked for an A4. But it also depends on whether the paper width is set correctly, but since not all sheets are the same size, it is a bit of a fiddly job if you have to check it every time you want it to be exact.