Can anyone name a retailer or marketplace that charges buyers an additional fee for basic trading rights?
Ebay don't charge for basic rights and protections which are mandatory under consumer law. The charge they make is for enhancements to these - such things as the money-back guarantee, and the right to return for items bought from private sellers that are recieved damaged or not as described.
Can anyone name a retailer or marketplace that holds sellers funds for an unspecified amount of time before they get paid?
My experiences of online marketplaces is fairly narrow, but certainly Vinted retain the buyers payment until delivery is confirmed, and only then pay out immediately if the buyer clicks the pop-up in their account messages to confirm that they are satisfied with item. Otherwise the payment is transferred two working days later as long as the buyer hasn't reported a problem. As Jon has said, ebay have almost certainly made their change to copy that.
....the market is now flooded with items (caused by free listing),
Not sure where you are getting that idea from - from the evidence of some of my regular searches, the number of items listed (especially from private sellers, who are the only ones getting supposedly 'Free' listings) is that the numbers of items have plummeted recently. Other members have made comments along similar lines in the case of their own regular searches. Where ebay is being flooded with cheap tat, it is principally from Chinese sellers selling via dropshipping through Chinese students and others who are located in the UK - countless similar or identical listings for the same thing from a large number of different UK based sellers. From what I have seen, these are mostly registered as business sellers so 'free listing' doesn't apply.
I do however largely agree with the sentiments of your post; ebay has (over the last few months) become a rather painful place for buyers and sellers who are not a business, and it certainly appears to me that a significant number of private sellers have stood back and stopped listing on ebay for now, and there is no doubt that having the added BPF is putting off a lot of long time ebay buyers (even where sellers have reduced their prices to take account of it) - both business and private sellers have complained about a significant drop-off in sales recently.
Both buyers and sellers are fielding many more complaints about postage problems, delays, and rejected compensation claims since SD started becoming mandatory for private sellers, and there were already enough complaints cropping up about PackLink when using their services was entirely optional.
Ebay is currently pretty much a 🐓-up in a tin hat.
