As part of Fish 4.1.x, the $__fish_data_dir variable is no longer used, as it's assets are now compiled into the binary (when built via cargo).

This is documented in the CHANGELOG:

https://github.com/fish-shell/fish-shell/blob/master/CHANGELOG.rst#deprecations-and-removed-features

zoxide needs to be updated to optionally use status get-file if available.

A PR is coming.