Would Pacific mobilization weaken a later convoy war?

Would the naval buildup against Japan leave Britain short of escorts in a later war against German U-boats?

Probably not: existing sloop, corvette, and Hunt-class escort programs would continue while industry expanded, potentially leaving Britain with a larger convoy force before the European war began.

The counterfactual does not require every shipyard to switch from escorts to capital ships. Britain had already begun programs for sloops, corvettes, and Hunt-class escort destroyers before the Tsingtao crisis. Wartime investment would expand turbine production and construction capacity rather than merely redistribute a fixed peacetime output. If the European war is delayed, more of those escorts can enter service and form a stronger convoy-protection force before German submarine operations begin.