I don't get direct taste effects but I get a vaguely metallic sense in my sinuses. Sometimes it's very metallic and generally goes with worse episodes, some anxiety/insomnia and other things.
For a time I thought I was copper toxic.
Now I understand that my condition is linked to gut issues and d-lactic acidosis.
IBD patients also experience metallic taste.
Just to let you know, lactic acidosis is listed as an acute condition, so there's all sorts of scary stuff about it if you start googling but this is not really the same. However it may well be that metabolites like lactic acid are playing a role in the fatigue and the results are not behaving in an acute way.
There seems to be a subset of CFS sufferers who have this rare disorder.
But I'm new here so please take everything I say with a pinch of salt