What does 'refund excludes service fee' mean?

Every Guaranteed reply on Lymion has two components: the price you set (or the creator sets) and a service fee added on top.

If the creator doesn't reply within 5 days, you get the price refunded automatically.

The service fee is not refunded. It covers the cost of running the guarantee itself, whether or not the message gets a reply.

Exception: if the creator deletes their account or blocks you while your message is pending, the service fee is refunded too, along with the price.

This is disclosed upfront on the send screen before you confirm a Guaranteed reply, not buried in terms you find out about later.