Your issue has nothing to do with AI.

Ebay do not allow members to exchange contact details and to do so goes against their policy.

This is part of the terms and conditions you agreed to when you began to use Ebay as a buyer or seller.

If you want to sell items that potential buyers can view before they pay, then you would need to sell elsewhere.

https://www.ebay.co.uk/help/policies/member-behavior-policies/membertomember-contact-policy?id=4262

Member-to-member contact policy overview

Members can send messages to each other through eBay. We encourage open communication between our members but we don't allow our members to use these options to send spam, offers to buy or sell off eBay, threats, profanity, or hate speech. We also don't allow members to exchange email addresses, phone numbers or other contact information, web addresses, or links within eBay messaging systems (for example, Best Offer or My Messages) or in any email communication managed by eBay, and all types of content posted on eBay by users, including listings, feedback, and reviews. eBay may monitor messages sent through eBay and between users for fraud, abuse, spam, and other violations of eBay's policies.