The car is a 1986 Audi 100 (5-cylinder KP engine, petrol)

In order to get rid of an oil leak, I've renewed the front crankshaft
oil seal, the front camshaft oil seal and the valve cover gasket.
Now there is oil coming out (in some volume) from the valve cover
gasket.

The only thing I can think of is in that renewing the camshaft seal
(and cleaning out the recess) I've inadvertently blocked the oil
return hole, or perhaps the camshaft seal is slightly too far in (it's
supposed to be flush with the housing) and is doing the same.

I don't think the valve cover gasket has been overtightened (it's
rubber) and I don't think the breather hoses got blocked during gasket
replacement.