I think there are quite a few reasons for the drop.
SD
BPF
Increase in postage costs
Poor service by couriers
Sellers being asked to change to a business etc.
For an example see my feedback page.
My yearly total would normally be around 900 - 1000 ,my monthly figure would normally be about 80.
I have only made about 10 purchases since 1/1/25 .Out of those 1 was wrong item,another was delivered to a neighbour when i was home,1 wasn't actually posted until 5 days after the latest estimated delivery date and another was posted 4 days after latest estimated delivery date and 1 didn't arrive at all (bogus tracking number ,seller now naru).
The above has put me right of buying but choice has dropped considerably so it's hard to find anything too buy 😐.