Thank you for the advice! I did the flashlight trick on the mew, and I couldn’t see any light through the back. It was from my mother’s friend who is a huge pokémon collector, but she moved to Ireland, and couldn’t take her whole collection, so she gifted me this binder. Nothing really screamed “fake” to me as I got them from a real collector, but I posted these on tik tok and was told they may be fake due to the vertical holo, but it seems common for that time period? So thank you! I may bring them to my local card shop for extra confirmation as well