how is it possible?

thanks for clarifying what they were talking about "therealgrowmie". Yes, you have a feminized auto flower, nothing photo about it Good luck

Yep, that can happen - but it's not really "half feminized, half auto." Feminized only describes sex, while auto vs photo describes flowering response. Autoflowering is largely tied to recessive day-neutral genetics. If an auto is crossed with a true photoperiod, the first generation will often behave mostly photoperiodic. But if the photo parent was carrying auto genetics, or the seeds are from a later/segregating generation, you can absolutely get plants that flower automatically under 18/6. What you're seeing is basically an auto/ early-flowering phenotype expressing from the cross. The 8-9 week veg period just makes it look more "photo-like" at first - some auto-leaning phenos simply take longer to trigger. So yes: genetically possible, just not because the plant is literally 50/50 in behavior.

In 8 weeks plants should be bigger.

Photo X Auto is called a semi-auto and they're often used outdoors in colder climates where you need flowering to set in before equinox to be able to finish the plants. If you want the plants to flower properly without risk of hermies and reveg, you should put them under 12/12 asap.

Seems like they’re just late flowering autoflowers, nothing to worry about. I’d keep the 18/6 schedule unless they start showing signs of light stress

It seems your seeds got enough auto genes to make them flower at 18/6 rather than 12/12 like a normal photoperiod plant. Nothing really freaky about it. I think you are mixing up the terms "feminized" and "photoperiod".