A few years ago eBay stopped allowing you to buy third party gift cards on the site by paying with eBay gift cards. They then added stricter limits as to how many gift cards you could redeem each day and month.
They’ve now added further restrictions, so you can only redeem up to four eBay gift cards per transaction. There’s probably limited inconvenience as a result of this change because the $1,500 monthly limit already limited how many gift cards you could use each month, but I’m sure there are probably reasons why this will suck for some users.