If you have both, I suspect that they have significantly more storage than your vintage fridge? In any case, if you buy a A+++ freezer they "only" use around 2

If you have both, I suspect that they have significantly more storage than your vintage fridge? In any case, if you buy a A+++ freezer they "only" use around 200kWh/year. This is mostly due to better insulation, and is in general an environmental and economical benefit to buy if your freezer is old.