I think this has always been the case , some sellers experiencing this more than others.
I rarely listed in auction format as my items had a ' ceiling' level for price, so buyers I felt would rather pay that price straight away without waiting 5 - 10 days for an auction to end.
The few auctions I made, yes, there were late payers, but most apologised not realising they had won the item, until eBay reminded them 4 days later to pay! Not everyone watches an item to the end, after nearly a week to wait, easy to forget one has bid!
You have some lovely items, but personally unless they are vintage or ' one offs' clothes do have a ceiling level and I'm sure if you revised those prices to Buy it Now prices you would not have this issue and perhaps gain more sales? Peeps looking for general clothing want to pay and receive them asap.
With a BIN format you can also select immediate payment required , the item then stays for sale until a payment is made.
Could solve your problems? 🤔
@mkclothes