After upgrading pip

Do you know why this error appears after upgrading pip?
why and what’s means?

Note it’s not only after upgrading pip but after creating venv also

An error occurred during configuration: option use-feature: invalid choice: 'content-addressable-pool' (choose from 'fast-deps', 'truststore', 'no-binary-enable-wheel-cache')

Find the pip conf file, and then remove the last few lines which are a section containing a variable set to 'content-addressable-pool'.
The pip config unset ... command will probably also work but I haven’t tried it before.

Nope. Pip config errors are fatal to all pip commands, including config.

avoid upgrading pip even if it tells you to. As long as your repls use nix modules config (I see that they do), any updates that you need will come automatically. Running this in Shell forces an update (as does making a change to .replit in the IDE):

echo "`<.replit`">.replit