Hi guys
Some years back (about10) I used uB hard shellac to finish a guitar
It’s been sitting in the study for a while - and I have just noticed these marks developing in the finish

It’s really strange

What can I do to fix it or even re finish it
Is it a matter of sanding it back and starting again82CAC5B2-AD97-43DC-BF4B-9CB049CBA2DA.jpg