Long term / chronic respiratory illness & recovery?

In 2021 I posted top 5 Regional MTB 4-6hr and top 10 National 12hr MTB results.

In 2022, I had 3 boughts of Covid which affected training and racing, then 3 different but continuous respiratory illnesses from Oct through to Dec, and again in March ‘23 which hammered my training. In October 2023 during a search for reason of chronic fatigue, I was diagnosed as having prior indications of Epstein Barr.

Since April then, I’ve had trouble with holding threshold and Vo2max power and recently after a 5 week training block posted a rested 3.1wkg FTP. In 2021 I was about 3.8wkg. With fatigue management in play, I’m also at 5-7hrs winter training (mostly z2 with a Cat C Zwift race or 40/20 power at vo2max session once a week) compared to 8-12 before.

I’m interested to know if anyone else has recovered from this and how - is it time -years? - to rebuild, rest, or am I forever capped at low ftp by my heart and lungs?

I don’t want to give up, but the constant disappointment in testing and back of pack racing is demotivating - I guess I find it hard to accept but am also aware that a Mono ( Mononucleosis caused by EBV) flare up can impact me at any time, one step forward and one step back.

Any sage words of advice or motivation would be appreciated.