Currently, when we set the copyright relationship it says X “is copyright by” Y, which is bad grammar. Presumably it's meant to say “was copyrighted by”. I think that's also not great, what we mean is “X's copyright is held by Y” (at the time it was published). E.g., if it says “© 2022 Penguin Group”, then Book X's copyright is/was held by [the] Penguin Group [in 2022].