Gfortran 10 added the default behavior to make type mismatches an error instead of a warning.
Legacy Fortran programs too often did not explicitly specify the procedure interfaces to allow implicit polymorphism.
The Fortran 2008 standard cleaned up this situation in part with
Workaround: Gfortran flag
-fallow-argument-mismatch can be used to degrade the errors to warnings.
It is however
to fix the problem in the legacy code, if it’s part of your code ownership.