The names used for Coordinate Systems seem to be random with spaces etc. causing them to sort out of sequence, especially where they are dated. This is the case in Australia with the various AGD & GDA datums. ArcMap was a bit better so see this as an feature parity request.
Pro - note how GDA2020 does not have a space thereby sorting out of sequence with the rest:

ArcMap doesn't have a space either but sorted them nicely:
