Be willing to use microdescs even if one bridge runs 0.2.2
In #4013 (moved) we fixed a big bug where clients would ask 0.2.2 bridges for microdescriptors, and then just fail. But we fixed it by falling back to normal descriptors if we ever get a hint that we have an 0.2.2 bridge. That fix is adequate for 0.2.3, but by the time we get to the 0.2.4 timeframe, 0.2.2 bridges will be rare. The fact that you fall back if you've ever seen an 0.2.2 bridge will make those clients rare and unusual (not to mention wasteful).
The better behavior, once 0.2.2 bridges are more gone, is to learn to avoid 0.2.2 bridges when asking microdescriptor requests, and only fall back to normal descriptors if none of your bridges can handle microdescriptors.