I agree there is definitely something going on with bigger pots - and air humidity for that matter (low humidity=faster onset of flower) - to extend the plants' lifecycle!
Whereby, since it's nature, there are probably a whole set of aspects that factor into how that actually plays out.
I've currently got a Mephisto Cosmic Queen going in a 56L fabric pot - though it's not quite full, so actual soil mass will be around 50L. And she got really nice 60% RH when she was small too. So she's taken her time building plant structure, and she is now also taking her time with flowering, to the extent that I'd say she's 2-3 weeks "behind" other grows in smaller pots.
That root theory sounds cool, in fact I recently read about roots sensing the size of the pot as early as germination, and that autos do best planted directly into their final pots because uppotting makes them have to re.orientate themselves - too bad I was on a surfing spree and didn't note where lol
I'd actually like to go back and review that myself!
But I've also had a plant that challenges this theory; a Sour Stomper I actually had to uppot from 28 to 40Lto get her through her grow - she obviously didn't give a shit about sensing pot size, just wantonly grew to the max

And she wasn't even slower to grow haha, ended up finishing in 70-some days, just like other sour stompers in smaller pots.
Concerning delays with autos, I've seen it go both ways - mostly downwards haha
But right now I have a second CQ growing in only 15L, she was supposed to get culled "better-of-two"-style but I didn't have the heart. So she got repotted into a 1L pot where she spent 10 days going
WTF?!?!, and then decided to grow anyway, which got her transplanted into where she is now.
Contrary to expectations, she has developed into a full plant,
and has stayed behind in her development by what seems to be pretty much the time she lost recovering from the initial transplant - her non-shocked sister has been stacking buds for a week, whilst she is still in the pompom bud stage. And while she also seems to be a different phenotype, I am intrigued by what is obviously proving the "time lost in an auto grow is
lost" theory at least to not be
inevitably true.
Now
why this plant is doing this where others didn't, not a clue!
Current pix of the Cosmic Queens via the link in my signature, it's Sunday and I'm lazy
Another perspective on the onset of flower would be one of survival.
While I don't think there are scientific studies on this, it's a known mechanism of plants that when they think they're going to die, they try and reproduce real fast to assure the continuation of the species. This is seen in the way weeds mostly grow - fast vegetative growth, fast flowering and seeding, the best bet in the dire soil conditions they have made their specialty. This reaction however is also noticed in ailing fruit trees, for example. And is probably also the reason why people thought of stressing their plants towards the end of flower to get them to move on more quickly...
Cheers!!