Me and another player both had fully maxed-out fishing rods (both containing Luck of the Sea III, Lure III, Unbreaking III, and Mending) and went fishing for a total of roughly seven hours of fishing and found no books containing the mending enchantment
Comments 2
Thank you for your report!
However, this issue has been closed as Invalid.
This is more of a feature request or a suggestion than a bug with the game.
We're very keen to hear your ideas though, so please head over to the Minecraft Feedback Site where you can search and vote for existing topics, or add a new thread if necessary.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki
Mending books are really rare, but they can definitely be gotten.