Apple Store liquid damage repair cost

Good morning, I went to an Apple store center for an iPhone 12 problem, I had very visible condensation in both rear and front cameras. But fully functional phone in all functions even cameras! The person who picked up the product changed the decision several times whether to have it open there or send it away eventually the phone was sent away. Presenting me with a cost-free repair quote under limited warranty. Handing me another courtesy iPhone for the period of absence of the phone. All at a cost of 0! After a couple of days I get an email from Apple stating that my phone had liquid damage and in order to fix it I would have had to pay 380 €.

But if the water problem inside the phone was known right away! And does Apple under no circumstances recognize liquid damage under limited warranty how is it possible that the invoice issued is not of the actual cost of repairing the appliance? 

[Edited by Moderator]