It’s like being a practicing or non practicing Muslim. Most of the “ex Muslims” are young people, it’s like a big fad now with Islam being In the news 24/7.
This is a massive stereotype of Ex Muslims (and Ex Mormons, Ex Jehovah's Witnesses, etc). They have been around for ages and ages (Abdullah Al Qasemi as a recent example in the 1920s I think), but of course the punishment for apostasy is so severe, and the family and communal shunning so harsh, that most that "came out" were buried under the family carpet or most just spent their lives living in hiding or secret.
I've worked with more Ex Muslims than nearly anyone, and the age ranges are extremely wide. On the internet there will be more between the ages of 18-mid 30s, but IRL it's very varied, in fact there are a lot of Ex Muslim parents who are in the closet. Some are great grandparents like this dude