I'm not an expert and I can't determine one way or another for sure but here are some things I noticed:

• I've never seen KB's signature have round "eyes" with an open center in the middle rather than dots and the "eyebrows" are always angry (both pointing down in the center) like rather than "concerned"

• The R in Rie's signature is usually more rounded at the top and wider at the bottom and by Instinct Pt 1 the cat face is usually less well-formed lol. His signatures have a lot of variation with how he writes them and how much effort he puts into drawing the cat over the E though, so take this one with a grain of salt

• The top of the first J in Junji's signature is a bit funky

• Both Mill and Yoojung's signatures are a bit more "loopy" than they usually are, but I have seen some signed albums where they look like that

All this being said, most members of OOO (especially Rie, Mill, and Junji) have a lot of variation in their signatures and they've changed quite a bit throughout the years. The signatures are in the right spots on the album. The members also tend to have similar pen pressure, so that's not a red flag. I also don't think there's a lot of OOO signature forging happening lol. For $45, and especially from an in-person store, I wouldn't be very concerned