I know a woman who identified as agender (as I do) when I first met her, and had identified as trans masc nonbinary for many years before that. As she moved through her 20s, she began to feel that she identified more as a gender nonconforming woman than a nonbinary person, and so she’s detransitioned.
Happily, she’s gotten very little pushback from the local community, and lots of support. She’s still a staunch trans ally and even feels bodily dysphoria – she just doesn’t happen to be trans herself after all.
I deeply agree that detransition is something that needs to be accepted and supported when it’s come to from a place of personal discovery and self-awareness. And that it’s vital to nonbinary people for these things to be discussed openly, freely, and with as little fear as we can muster.