Higher drag with a seized engine.
All discussion of how the windmilling fan is extracting energy and thus must be creating more drag ignores the fact that a seized engine is essentially a giant blunt body with all kinds of intake spillage going on. That effect is way more than the windmilling. (All the windmilling needs to do is overcome the bearing drag once the engine is stabilized, which is not that big)
Am aware of an incident where significant engine damage caused one of a twin to seize. Max attainable altitude dropped from the theoretical ~25kft for a normal OEI case to below 15kft.