This is basic thermodynamics stuff.
Looks like energy used in datacenter in 2018 was around 200TWh. If you use all this energy to heat only the mediterranean sea, you will have a change of temperature of 0.00006°C.
FYI, your comment is wildly misleading. Thermal pollution is real and has a wide research literature.
The worry is not that that the average temperature of the oceans will rise. The worry is that the local temperature of the ocean will rise. This is exactly what happens with other forms of thermal pollution. One example studied for decades was California's San Onofre nuclear power generating station. It has been subject to regulations regarding its thermal pollution into the ocean. They built long pipes so that the temperature increase from the cooling water could heat the ocean gradually over a wide area rather than severely in a narrow area. It's the same principle as a CPU heatsink.
For what it's worth, I personally found your comment quite distasteful. Instead of trying to understand what you didn't know, you knocked down a straw man and pretended like it was obvious and backed by science.
I used this calculator https://www.omnicalculator.com/physics/specific-heat