Breast milk changes when frozen?

FTM here. I have a stash of frozen milk that I am just starting to use for my LO when at daycare. I am not sure why but I have had this fear that the older bags are bad and my LO shouldn’t have them.

I am probably crazy but I unfroze two bags and tasted a tiny bit of them. Both were kind of funny tasting not sweet like fresh milk (I tried once when she was refusing the breast one morning and tried this morning because of this fear). Question is - is it normal for the taste to change over time when frozen? Could it be because it’s from when I first started breastfeeding so the components were slightly different? Should I throw it out? Thanks for any advice.