For those looking to replace their Golden Polymer Matte varnish with UVL protection that was discontinued, Golden now has come out with a new Waterborne varnish. Currently it is only out in gloss version but according to this article they are working a matte version to be out soon. It is possible this gloss version could be matted down using the corn starch method but I do not know. If anyone gets any and tries it please post results here for us.
At the very least, this could be applied as the first layer underneath the matted version you are currently using to give it UVL protection. This varnish is a removable varnish so they recommend applying an isolation coat first, which they also sell now. However, if you apply it and then put a permanent varnish such as Soft Touch corn starch mix over it then the Soft Touch would make the whole surface permanent.