Are pregnancy related Attention span issues a thing???

I have never had a problem with sitting for long periods of time and focusing on a task. In fact, powering through and becoming fixated on what I’m doing has always been a norm for me...to a fault at times. It was even common for me to completely forget to eat while I was focused on work. But for the last week or so, I feel like I literally cannot pay attention to what I’m doing for more than 10-20 minutes at a time and it’s super annoying. Are attention span issues normal in pregnancy? If so, this is literally the first I’ve ever heard of it. I’m 31 weeks.