Cheese releases excessive oil

Cosmetic

A cheese-choice or overbaking issue.

Ask yourself

#1
High-fat cheese baked too long or at too high a sustained temperature
Generally accepted
Extended heat exposure breaks down cheese proteins further, releasing more of the fat they were holding.
#2
Cheese blend skewed toward high-oil-release varieties like cheddar without a stabilising cheese
Generally accepted
Some cheeses are simply more prone to oiling off than others when used alone.

The same symptom has different answers on different equipment. Each branch below states how to tell whether it is yours.

Pizza in a domestic ovenStrongly supported
How you would know: Oil has pooled on the surface after a bake of eight minutes or more, particularly with a generous cheese layer.
The cheese has been held past the point where its protein network contracts and squeezes out fat. A long domestic-oven bake keeps cheese at temperature far longer than a 90-second high-heat bake does, so it passes that point routinely.
Do now: Blot the surface with kitchen paper — the oil sits on top and comes off cleanly.
Change next time: Pull the pizza as soon as the cheese browns rather than waiting for more colour, use slightly less cheese, and consider adding it partway through a very long bake.

Blot excess oil with a paper towel after baking

Blend a high-oil-release cheese with a more stable one, and avoid overbaking

Guides that treat this as an outcome to improve, an environment to work with, or a flavour to understand, rather than only a problem to fix.