I was sus on it, thanks for letting me know how they make them

So if it's a photo period crossed with an auto, how is it still photo period? Which one would be to pollinate the auto or photo period plant?
Putting it at as simple as I can photoperiods will dominate the cross as its a dominant trait, autoflowering is a recessive trait that will be hidden if crossed with a photoperiod for some time until it pops back up a few generations later.
So photo X auto (or auto x photo) =
1st Generation (f1) = 0% auto and 100% photo
Cross a male and sister from that generation and you have F2
2nd Gen (f2) = 25% auto and 75% photo. this is when some autos begin to show up. Cross 2 of the autoflowering siblings and then
3rd gen (f3) = 86% auto 14% photo
cross another 2 auto siblings and
4th gen (f4) = 96% auto
So it pretty much takes 4 generations to make an autoflower from scratch.
So back to your question, they normally hit a photoperiod plant with autoflower pollen to make f1 seeds (pollen chucking) and will call it a 'fast flower'.
Some plants might be faster than the photoperiod mother but it's not always gonna be the case because all these new strains have wide/diverse genepools with so many different genotype expressions (the genetic makeup and combination of alleles which determines observable physical traits known as phenotypes)
Physical traits (phenotypes) include bud structure, height, smell, leaf morphology, colour (green, red, purple, black) etc
So it's basically a lucky dip sifting through these unstable, unworked seeds because there's been no effort to segregate traits by selective breeding. This is what seperates a pollen chucker from a breeder.
A breeder will selectively breed strains way past the F6 generation, by f10 you could pretty much call it an heirloom variety as most of the siblings will express identical homogenous traits between eachother.
There's plenty of photoperiods that can be finished around 45-50 days of flower.
No need to cross them with autoflowers