If youre going around the world, you're going through multiple connection points which will absolutely add up. Going from LA to NYC, it probably wouldn't be.

And these data centers satellites are small. Stop thinking massive things, they're going to be like the v3 starlink dishes but a little bigger. They're going to launch multiple data center dishes per launch like how starlink v3 will be 60, not 1 or 2. SpaceX already knows how to radiate heat away on the satellites they launch, this isnt going to be an issue for them, they already do it today.

Edit: like size wise you need to be thinking like a server rack, plus the huge folding solar array/radiator for it. They already know how to make the folding solar panels as well. And the rack will probably be long and narrow so they can angle it best against the sun so it gets as least heat as possible from it, not a chubby thing with a lot of surface on all sides.

Edit: also land based routing isn't direct increasing the distance likely substantially, potentially more than the up and down, the massive starlink constellation it will be more direct.