Cargo Features

[dependencies]
s3-tokio = { version = "0.39.3", default-features = false, features = ["no-verify-ssl", "fail-on-err"] }
default = fail-on-err

The fail-on-err feature is set by default whenever s3-tokio is added without default-features = false somewhere in the dependency tree.

no-verify-ssl
fail-on-err default

s3-tokio has 3 features without comments.