There’s a possibility the OP may not be back to fill in those little annoying things called details but let me throw something out there.
The OP says they “recently had a coolant leak”. Then they had the water pump, timing belt, etc. replaced.
What has been left unsaid here is the story behind the coolant leak.
How long was it leaking, how much overheating may have been involved, etc.?
If the car was overheated it’s possible a head gasket could have been hovering on the edge of flat giving up.
The shop replaces the t-belt, water pump, etc. and the car runs fine.
About 5 minutes after the OP left the shop the engine temp is rising, the cooling system is now pressured up, and a shaky head gasket has decided to buy the farm.
In a case like this it’s not the shop’s fault at all and the OP is simply a victim of circumstance; although continuing to drive an overheating vehicle is a self-generated circumstance.
Just theorizing without details anyway. What do you think?