Cargo Features

esplugin has no features set by default.

esplugin = { version = "5.0.1", features = ["compressed-fields"] }
compressed-fields = flate2

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

flate2 compressed-fields?