Weird lifting experience at the gym yesterday, any idea on what may have caused it?

Yesterday at the gym, I was feeling weak and sluggish thanks to my recent diet for the last 10 days (very low carb, 700-ish calorie deficit as 40yo male):

May 24th 11am

Shoulder Press DB

• 3 reps x 50lbs
• 10 reps x 35lbs

Zercher Squats

• 4 reps x 95lbs (SS⬆️)

Incline Bench Press

• 8 reps x 115lbs

(my full workout, ~10 minute rests between sets)

I did the Zercher Squats after my first set of seated dumbbell shoulder presses before starting my final set of seated DB shoulder presses. All year, I have NEVER done more than 3 repetitions of the shoulder press. It's been my go-to exercise and always my first set at the gym everyday as a beginner (while kinda/sorta emulating the "greasing the groove protocol" by famous strength coach Pavel).

Prior to my diet which started 10 days ago, I would always do my 2nd set of shoulder press as another triple (1 set of 3 reps) of 50 pounds but I honestly struggled to get 3 reps while fresh and didn't want to fail on getting 3 reps so I just grabbed what I believed to be an easy weight which I could blast out 10-20 reps because I wanted to know what my max rep-count could be for a very easy weight.

However, after my 3rd rep using the 35lb dumbbells, I felt an extremely unusual phenomenon in my brain where I felt as if my "autopilot" had shutoff and now I had been given full 100% control and responsibility for finishing the remaining reps "myself" as if that part of my brain which had been training 3 reps per set all year simply turned off and passed control back to my executive center of my prefrontal cortex. It was much more effortful and mentally draining, feeling as if I had to expend unfathomably more exertion on reps 4 thru 10 than 1 thru 3.

The feeling could best be described as similar to sci-fi movies or tv shows (specifically "Travelers") where your consciousness is sent inside a new person's body in the sense that I felt like I was doing something new and that I'd never done before. (i.e. the same feeling I had earlier this month on my very first rep of the hip thrust machine which I'd never done in my life) It was that same "fish out of water" feeling like I had no idea or familiarity with this exercise and every since motor unit recruitment in my delts had to be manually exerted by my consciousness rather than being done "automatically" while just sitting there.

Another way I could describe it is a feeling that my motor cortex simply "gave up" and passed control back to my executive center after 3 reps, similarly to in programming when a function call is executed and the callee sends back the return statement and/or control to the caller.

I'm a very curious person by nature and want to know if this phenomenon has a name so I can learn more about it? It was absolutely the weirdest feeling I think I may have ever experienced in my life. It was made more surprising in that it was completely unexpected and occurred at a random moment of an otherwise boring, uneventful day. I love listening to neurology podcasts (such as Huberman) and I love learning about neurology, specifically those split-brain experiments done by Dr. Perry where you cover one eye and are shown a picture (such as a red spoon) and each hemisphere of the brain confabulates a different reason or narrative as to why you chose the red spoon over the blue spoon.

My 2 questions today are if that phenomenon has a name where you only do sets of 3 for a really long time and your brain seemingly short-circuits and is unable to extend that "greased groove" past 3 reps? Lastly, have any of you experienced similar or otherwise interesting neurological phenomena unexpectedly at the gym? (and if so, please share it)