Is this normal for books from Folio or Easton Press?

I only recently started collecting books from publishers like Folio Society, Easton Press, and less expensive ones as well like Everyman's Library and Library of America.

I've frequently gotten books where the text block is either slightly or fully detaching from the backing of the book, if that makes sense. I'm not sure what that part the text block attaches to is called. I'm also not sure if this actually affects a book's long term durability in any way. Is it considered a defect? Because with how often I get books like this, I'd be surprised if it was considered a defect.

I've included a link to some pictures, hopefully it's clear what I mean.

https://imgur.com/a/LCAgOI0

What you’ve shown in your images is normal for sewn binding books. They are not glued to the base boards like modern standard trade hardcovers. This is actually an improvement on the books quality and durability, not a defect.

Absolutely normal, and as >2 HowardEriksonWolfe: noted, more modern and cheaper books are glued to the base boards. Higher quality books are sewn and not glued.

Agreed, perfectly normal