The body needs cortisol to function. When you take prednisone for more than a few weeks, your adrenal glands make way less cortisol. If you stop prednisone or taper too quickly, your body won't have enough of the cortisol it needs. Withdrawal symptoms are due to that sudden cortisol shortage.
https://www.mayoclinic.org/prednisone-withdrawal/expert-answers/faq-20057923
The treatment for steroid withdrawal syndrome is more prednisone. Increasing the dose of prednisone continues to suppress the adrenals and continues to cause a cortisol shortage when Prednisone is tapered lower again. Without enough cortisol the body's ability to regulate inflammation is reduced so chronic inflammation continues and flares and more likely.

IL-6 inhibition reduces inflammation but doesn't suppress adrenal function. When inflammation is stopped the need for prednisone is reduced. Less prednisone allows the adrenals to recover and more cortisol is produced ... hopefully.

Sometimes the adrenals never recover and this results in Prednisone dependence. Usually the adrenals will recover if given enough time.