I did find this paper where somebody used the term “mindless reading”

Smallwood, J. (2011). Mind‐wandering while reading: attentional decoupling, mindless reading and the cascade model of inattention. Language and Linguistics Compass, 5(2), 63–77. https://doi.org/10.1111/j.1749-818x.2010.00263.x

Seems that is the term used for it such as this talk in 2006

https://ies.ed.gov/director/conferences/06ies_conference/posters/readingtq_reichle.asp

Abstract: "Mindless reading" occurs when, during reading, our eyes continue to move across the printed page in spite of the fact that we are busy thinking about things that are often completely unrelated to the text.

Adhd

Back when I came into the office every day, it was a 45-minute commute. At least one day every week, I had no active memory of getting from the north side of the beltway to my house (about 20-25 minutes). I'd reach this point, and it was like someone flipped a switch, and I became aware that I existed.

I've done this with Audio Books. I've listened to 2-3 chapters, and they'll mention an assassin; Brain goes, wait, assassin? WHAT ASSASSIN? I start rolling back find out I completely tuned out 20 minutes of the story.

This is why studying takes me 4 times longer than the average person. I have to reread so many things to make it sync in. It annoys me how somone can just look or read something once and they have it already

This was a symptom of ADHD that I discussed with my doctor when I got diagnosed tbh

~~Cruise control.~~
Autopilot, like Szeth said below.

Thank god this relatable to so many of us, I was wondering if this was a symptom of a larger disorder whenever this happens to me.

The worst is when I'm reciting word for word technical information about chemistry or physics, because I often like to explain how things work to friends and family while I work on stuff, and then I'll get interrupted or distracted and have no memory of wtf I was just saying for the last several minutes straight.

I call it “ADHD” because I damn sure was thinking about 3 other things while I was reading-notreading.

It’s called ADHD.

Surely there's a very long German word for it.

It's called "looking at memes".

!nameit@sopuli.xyz

I think it could be argued for a state of hypnosis, like how people drive for miles but just don't remember how they did it entirely.

Difference is, you clearly drove and got there safely. You didn't read the words on the page, you just moved your eyes across ink blots.

I've done this with audio books.

I vary between spacing out, zoning out, or the already mentioned autopilot.