There's so little to go on - other than you think you might have a problem worth checking.

I have years of training logs that demonstrate what level of fitness i was at across several decades.

If you have never tested and recorded any of your races or workouts - then trying to determine whether you are aging normally will be impossible. If you have a specific medical issue - then the question isn't really cycling related. You might want to compare yourself to other family members your age - rather than ask cyclists about your well being.