No good at all.
That's a quick drop from 20mg down to 5mg in only five months. I started prednisolone two months earlier than you and am only down to 6.5mg so far, following the recommended reduction schedule. From what I see on this forum, the thing most likely to bring on a flare is reducing too quickly or by too much at a time. Reduce by no more than 10% of the dose each time is a warning often given. Were you just reducing too quickly do you think?