Firstly I would say that carshop are not up to speed.
Revo has a page for this here
https://www.onlyrevo.com/blog/will-revo-software-invalidate-vehicle-warranty/
Seat Customer services confirmed this:
Thank you for your recent contact with SEAT Customer Services.
We would recommend that any alterations made to a vehicle or any parts used on your vehicle should be SEAT approved. If this recommendation is not followed and a non SEAT approved part/accessory is used on your vehicle and a fault occurs as a result of the use of this component then your warranty will be void.
If also you turned on any features of a component that did not come as standard on your vehicle and that component broke the cost will not be covered by SEAT and in doing so the warranty on any related parts can also be affected.
I hope this information proves useful and if you do require further assistance please do not hesitate to contact me on the number provided below.
The general consensus is if you modify the power output and the dealer detects it (revo have a link to current status on this) then they can and do reject warranty claims on Engine and Gearbox as you have modified the car with non Seat Approved Parts and creating power that it was not designed to have (even though it will happily support the extra power)
However if you lights stop working or your digital dash stops then that will be covered.
It's a very grey and murky area.
However if this is a carshop warranty then the rules may be different.