Summary

The very end of the section https://docs.astral.sh/uv/concepts/configuration-files/#configuration-files says

uv also accepts a --config-file command-line argument, which accepts a path to a uv.toml to use as the configuration file. When provided, this file will be used in place of any discovered configuration files (e.g., user-level configuration will be ignored).

The option can also come in (rather hidden) via UV_CONFIG_FILE, which was the case for me.

The effect of this option is very powerful - I would claim more powerful than what users intuitively expect.
Its use should thus be mentioned in verbose output.
Right now, it does not even show up in trace output.

Example

Such a line could look like the following:

DEBUG --config-file/UV_CONFIG_FILE is set to /foo/bar/uv.toml, ignoring all user-level configuration