@bristolsc 

Apologies - the phrase "a credit card when the card is first used" which I used may have been a little ambiguous; I did not mean a completely new credit card, I meant a newly issued credit card with new start and expiry dates (the type which is issued to existing card holders when their current card reaches its expiry date).

My current card, for example, was issued just over 3 years ago and has an expiry date of 2026; it replaced my previous card with the same provider, an account with whom I have had for well over a decade. The first time that card was used was therefore regarded as 'first use' and it may be that the first time such a card is used without the CVC number being required triggers a temporary pre-authorization £1 payment hold whilst the card details/account are verified.

I don't know for sure if that's what has happened in the reported cases on these boards but in the absence of any other explanation it is a possible reason.

Failing that such a sudden increase in temporary pre-authorization fees may well be explained by a change in eBay's processing, as a buyer actually pays eBay for a purchase rather than paying a seller direct. If eBay changed any part of their payment processing a card issuer may well register a transaction as 'first use' which triggers the pre-authorization hold. And in the absence of any proper confirmation by eBay, rather than the usual "it's not us" denial and deflection, I have to say that's probably the more likely reason.

I last used my credit card, through PayPal, for a purchase on eBay at the beginning of this month and no £1 fee was included at any point. If a fee appears on my next purchase that, to me, will confirm the above has happened. I'll let you know if that happens.