I honestly do not know if its related to COVID or if I'm just getting older and my body / mind are finally starting the inevitable downward spiral that takes place over the next 30-40 years.

It's hard to say for sure. All I can say is, relative to who I was in 2019 I feel like I'm easily 50% of that person both physically and mentally. Maybe that's "natural" for someone in their mid-30s, but to me it feels a little accelerated.