Rejection Warranty - Decoupling Mat

I'll bring up this topic now.

We have new screed coming up and it is to be covered with 20x120cm tiles. A master tiler recommended decoupling mats to us because it is fresh screed that could still settle and additionally large-format tiles. However, he also said that this would involve significant additional costs, according to the offer 33€/m2 extra. What are your experiences here?

With our tiles, decoupling was also done!