In the tooltip, when hovered over in a specific way:

The tooltip is added from .lang file and is technically correct. The artifact that you see are Line Feed characters that are incorrectly escaped by Minecraft when there is enough screen space to not split the tooltip on multiple lines.
A workaround is to write a resource pack that removes the line feeds, for example, overwrite
item.witchery.extended_biomes_book.tip=§oCraft the book with a piece of paper,\n§oto copy the current biome page (used\n§oin some rituals).
into
item.witchery.extended_biomes_book.tip=§oCraft the book with a piece of paper, to copy the current biome page (used in some rituals).

Despite searching for a bit, I couldn't find a bug on the mojang tracker, but I found numerous forum posts talking about this (https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/resource-packs/resource-pack-help/3032679-text-to-another-line-name-of-item-in-lang-folder)
Closing as Vanilla bug