Updating symfony/symfony from 2.8.19 to 2.8.20 breaks the link generated in twig by asset($asset, $package) is broken form some files. Reverting the version makes it working again.

I do not yet see any pattern which links are broken. Some file from the same directory do work, other do not.
The generated link is "/js/some.js" instead of "/path/to/installation/js/some.js" (in dev and prod).

Any idea how I can find out more details?