Unless you've lived abroad as long as I have (28 years, or 30 years if you include the 2 years I lived in England), it's difficult to explain why I no longer feel Scottish.
I've already given the reasons for the growing feeling of detachment since the 2014 independence referendum, followed by the subsequent political events in the UK. Other factors are simply the passage of time and the weakening of family ties with the deaths of close relatives. So when you add all that up, pretty much all of my sense 'Scottishness' has now dissipated. Nowadays, when asked where I'm from, I say I'm Belgian. Unlike TRVMP it's not because of any sense of national pride, but simply because it's factually correct as I'm a Belgian citizen and it's been home for the last 17 years.
I guess it's down to a feeling of belonging, and because both myself and Scotland have changed so much since I left in 1996, I no longer have any feelings of belonging. On the increasingly rare occasions I do visit Scotland (typically nowadays it's only for funerals and the occasional Ton match), I now see it through the eyes of a detached foreigner.
Like TRVMP I still follow the Scottish football team and will also be rooting for them in Euro 2024, but that and of course the Ton are really the only emotional attachments I have left. So while the football may still be in my blood, Scotland the country no longer is.