GLL - RonCla and Steve Nobel are correct - too heavy of a coat of the clear was applied and the solvents in the clear "activated" the solvents in the metalic paint which cause the metalic flakes to run.
when you spray the clear coat you want to apply at least one but preferably 2 or more thin coats just to dust the paint with the clear. \
Clear coats can have highly aggressive solvents that will "melt" or reactivate solvents in the paint coats below - especially "enamel" and "2K" clear coats.
the only way to fix it is to strip the paint and reapply the paint and the clearcoat
Cheers
John