What other variables changed? (eg telmisartan, dapagliflozin, cardio zone 2, reduction in doses, etc)
Yes the heart "stiffens" with the use of steroids, the contraction part gets really strong in juxtaposition to the relaxation - the diastolic part.
The opposite happens in endurance at the athletes - their contraction is weaker compared to the relaxation.
This creates asymmetrical cardiac function, characteristic of heart failure. Under the echo you see the heart beating completely 'wonky'.
Cardio zone 2 helps balances out cardiac function for us bodybuilders with strong contraction, so if you implemented zone 2 and reduced your anabolic load these past 3 years it could help explain.
There seems to be evidence of tb-500 with cardiac cell damage regeneration. (Steroids can cause apoptosis in hearts cells, through several pathways.)
There is also the component that the echo is operator dependent and the values of your EF can change according to who does the test. The sensitivity for function would be better viewed through strain echocardiography with speckle tracking, which allows the 3d mapping your heart and allows the echo to track the beating to better see the contraction and relaxation of cardiac muscles.