A similar thing has been happening to me for months now.
Using sell similar on an item, I have to carefully check the postage option is still set to ' Postage Only' as every second listing becomes Collection only.
Others reporting sell similar changes their ' No Returns' policy to ' Returns Accepted'. Some sellers noticing too late, after an item is sold.
Many a strange happening on the site of late ! 🤔
@grast_1369