For me, the sober journey so far has led to change in pretty much every corner of my life - both physical and mental. Initially my emotions were really all over the map, and I was probably more nostalgic as my brain was finally waking up from a 25 year self-induced coma. After that I started working on underlying conditions with a counselor, so that also was a major factor in my way of thinking, and also increased my level of self awareness. I'm also almost a decade older than I was when I first started taking my sobriety seriously, so there are likely pure time factors in the way that my mind and body have changed with age. The pandemic and all of its related/lingering factors will certainly have changed me too as we look back over time.
All of those things are factors and there are probably many more, but I do make a concerted effort to be more in the present - which does help turn me towards the future vs the past. I think that is a good thing to be honest - while being nostalgic can be a pleasant experience, it can also become an obsession and hold us back.