Moser Baer CDR's - Bronzing

I have a couple of small stacks of “Windata” CD-R (the house brand of the US “Micro Center” computer stores) which are made by Moser Baer. They are perhaps a year or two old.

On one stack, the reflective layer now has a uniform, but very distinctly light bronze appearance especially when compared with the other stack which is bright silver.

I kind thought this phenomenon was a thing of the past, even with bargain (and now defunct) brands.

If Micro Center continues to feature store brand CD-R (their optical media aisle keeps shrinking; originally one full-length aisle and now one-quarter of an aisle) I wonder who they will source from … probably UmeDisc I presume as for their DVD and BD blanks.