There are different kinds of weed smokers. There are those who use it to get "stoned" and those who use weed to get calm and focus.
Stoners do bong hits until they are so stoned they fall asleep or run out of weed. I've never made a habit of that. I use a small pipe that holds about one bong hit and load the bowl just a few times a day and take tiny tokes off it when I take a break from coding.
I've been using weed like this since I was 12 years old in 1971, so for more than 50 years now.
During those years I learned how to design and engineer and build custom cars from the ground up. My father worked at "Barris Kustom" and I learned from him and others who worked there. From there I went on to work building advanced driving systems for C4-C5 quadriplegics, and the mod needed for wheelchairs they used.
In my late 20s I decided to learn how to use computers with the intent to learn how to code. I made my first "app" in the late 90's. Made my first website in `99, and my first web app for a single user in 2001 and released it as a multi-user app in 2002.
I'm 63 years old now. A couple weeks ago my wife asked me to go look at a friend's car. It had been sitting in their driveway for over a month because it wouldn't start. The car belongs to two guys who are a couple. Neither of them smoke weed. They like to drink on occasion but they're not everyday drinkers. They're both in the early 30s.
So I grabbed a few tools and went and looked at their car. When I got there the battery was dead. So I hooked up some jumper cables and after getting enough of a charge to get the gauges to work and the engine to turn over I tried to start it a few times and then told them what was wrong with their car. "It's out of gas".
I am sure there are those who'll dismiss it because I've been dismissed on this subject most of my life, but there's a point to found in that story that is relevant to this topic, which I've also seen come up over and over most all of my life.
Studies like these that attempt to find a link like this will most always conclude they found one because they're akin to wearing blinders to everything else that might also be a cause for the effect they cite.
If those two guys smoked weed the first thing most people who don't smoke weed would conclude is that is what caused them to not realize their car was simply out of gas.