After Actemra was started ... what was the prednisone tapering recommendation that your doctor suggested? It takes about 6 weeks for Actemra to be effective so the tapering process starts slowly but I found that I was able to speed up the tapering process substantially after 6 weeks.

A high dose of prednisone is considered to be anything over 30 mg for most people. Side effects are probably inevitable at high doses. "Moon face" and weight gain are obvious side effects.

There are many other possible prednisone side effects that aren't so obvious and sneak up on you. Blood pressure should be monitored frequently and this can be done at home. I wasn't so diligent about checking my blood pressure until I got extremely short of breath and perspiring profusely. I thought everything was fine because I was pain free. I felt reasonably well until I couldn't walk up a slight incline without stopping to rest. Even a shower was exhausting. When I reported an irregular pulse to my primary care doctor, he ordered an EKG which said I had left ventricular hypertrophy (LVH). That was when I was told to check my blood pressure more often. Only then did I discover my blood pressure was extremely variable and sometimes it was in excess of 210/110. Prednisone can impair many physiological regulatory mechanisms that the body relies on.

"Fluid retention is one of prednisone's most famous side effects. "Moon face is common, which is swelling in the face that can occur after you've been on steroids for a long time." It may be common but it isn't normal.
https://health.clevelandclinic.org/8-prednisone-side-effects-how-to-minimize-them
Reporting all symptoms to your doctor that don't seem right is the best thing you can do.