Fiber 2.50.0 (Go web framework) contains breaking changes – function signature changed – that breaks dd-trace-go (DataDog tracing), fix will come in the next dd-trace-go release. Details in [BUG] gofiber/fiber v2.50.0 breaking changes · Issue #2275 · DataDog/dd-trace-go. I stumbled upon it after merging Dependabot PR that broke the application.
Lesson learned - Go packages aren't strictly using SemVer, so MINOR version can have a breaking change. Beware!