Edit: Further research has shown this to be fatty bloom or spew. The test was to apply heat with a hair dryer. If it's spew the fat will warm and dissolve back into oil, which it did. So fixing it is the issue now.
I have this issue with my leather projects. At first I figured mold/mildew. But research also says it could be "fatty bloom" or spue/spew... Which is when oils/waxes migrate to the surface and oxidize
There is no musty smell or scent of damp/rot that one would normally associate with mold/mildew. The film feels somewhat, well, filmy or greasy. Makes me think fatty bloom but I don't know for sure.
Any advice on how to get rid of it on existing projects and how to prevent it in future projects?
Picture of what I am dealing with...
Mike