When there's a change of bank details,  eBay you must appreciate,  must take all precautions and checks they need to make,  as they need to know the genuine owner of the account is making these changes,  and the account has not been hijacked.  For security reasons the checks and length of time to make them,  will not be revealed.

You could contact CS ask if they require any more forms of verification perhaps the sending of micro deposits to your new account.

Contacting eBay Customer Services is not easy nowadays to get a live agent , but some have had success using the app, otherwise keep typing in ' I wish to speak to an agent' and this too can work.

Use this link to contact CS, if you can try at 8 a.m. on a weekday morning also more chance there for Dublin to answer.

https://www.ebay.co.uk/help/eua?id=5190

Lines open between 8 a.m. to10 p.m. on weekdays.

9 a.m. to 6 p.m. on weekends.

@rob_20222