Prednisone has lingering side effects after we taper off. When I tapered off prednisone, having no energy lingered for more than a year. In my case, the low energy level was related to a low cortisol level.

Taking prednisone long term may affect your adrenal health. Tiredness and fatigue are often symptoms of adrenal insufficiency. This side effect of long term prednisone use may take months to improve. This particular side effect is why we need to taper off prednisone slowly.
https://www.verywellhealth.com/does-prednisone-tapering-minimize-withdrawal-190242

The other side of tapering off slowly is to take Prednisone for the least amount of time as possible. It is difficult to do both.