In the search fields for the crafting book and creative inventory, typing a single digit will return some tools and weapons whose item descriptions do not contain that digit anywhere.

Example (see picture): Typing '9' returns, among other items, a netherite axe. The digit 9 does not appear anywhere in the tooltip for this item.

EDIT: I have done some further investigation, and variations of this bug seems to have existed ever since tool attributes were introduced in 1.6 snapshot 13w21a. However, in this version, the bug exists in a slightly different form; the digits 0-8 all work correctly and show only the tools with that digit in their attribute. However, entering '9' shows every single weapon/tool (except hoes, which have no attack attributes) of every type. It also shows all variations of swiftness and strength potions, which are not affected in newer versions.

EDIT 2: It seems that the original bug from 1.6 was fixed in 1.8 snapshot 14w32a. There is no mention of this anywhere, because as far as I can tell a bug report was never made for the issue. This new bug was introduced at some point during the development of 1.12. However, it is currently near midnight for me, and I have neither the time nor patience to figure out exactly which snapshot this occurred in. See you in the morning.

EDIT 3: Done some more searching. This new bug was introduced in 1.12-pre6. The changelog for this version includes "Optimized recipe book and Creative inventory searching", which is presumably where this issue slipped in.