Members were informed of this change,

Ebay sent an email on 19th december 2025 to inform members that Inpost was now available for items posted using Simple Delivery.  All members were automatically opted in.  The service became available in January.

There was a link in the email to opt out.  The paragraph below is from the email - the link no longer works but you can go to 'postage preferences' to opt out.

InPost is enabled already, so the delivery option will be available to your buyers without you needing to do anything. They’ll start seeing this option from Jan. If you’d like to opt out of InPost, you can do so at any time in your Postage Preferences. We recommend enabling all couriers, so you get the most competitive rates and r...