Even without formal immigration controls for transfer passengers I'm sure the European authorities are quite capable of consulting the flight manifests and arresting you in transit if they desire.
Re:Coinbase Halts Operations in Japan
by Scoundreller on Thursday January 19, 2023 @02:51AM
(#34437783)
And if ETIAS ever goes live, they’ll be pre-clearing just about everyone before they get on the plane.
So flying from UK to Mexico with a stop in Miami will involve immigration and all the jazz in Miami (including the need for a visa if your passport normally requires it).
This is usually not the case in Europe. You stay in the non-schengen transfer zone and walk from one gate to another.