It's really hit or miss with me. Sometimes I'll get into something and just disappear for 15 or 16 hours as I invest myself into it, and other times I can't focus on something for more than an hour. It's definitely gotten worse as I've started coming out into the world on my own more and stopped relying on others for anything. And then again, it depends on what I'm focusing on. I can still sit and watch through an entire season of anime 4 or 5 days out of the week, but if I try to sit down and play a video game I'm just sitting there bouncing my knee and watching my phone to keep track of time.
Maybe it has to do with being afraid of immersing myself into something so deeply that I lose track of reality? When I write up posts for roleplays I can disappear into a google doc for three or four hours and just zone out with some instrumental music on my headphones, but I've been doing that long enough now that I know roughly how long it'll take to finish writing that post. Maybe now days it's not so much about how long I can pay attention for, but the idea of knowing how long each activity I'm going to partake in will take out of my day. With the things whose time is roughly known I can indulge myself freely knowing just what kind of chunk I'm devoting to that hobby, but for anything else where there's not a clear or known goal it's more of a worry of wasting that time. If I stop halfway into a three hour gaming session because I just don't feel like playing, then I feel like I've wasted that hour and a half and sit there moping, wasting away the other hour that I could have been doing something else and then I'll blame my emotions at the time on my gaming experience.
