For 14 years, starting with Go 1.0, encoding/json shipped with known problems, such as case-insensitive field matching, that were never fixed. This book traces the road to encoding/json/v2, formalized in Go 1.27, through the issues, proposals, Gerrit changes, and standard library source that shaped it.
https://www.ymotongpoo.com/books/go-json-v2-history