allout-enable-file-variable-adjustment is a variable defined in `allout.el'.
Its value is

  • Automatically becomes buffer-local when set.

If non-nil, some allout outline actions edit Emacs local file var text.

This can range from changes to existing entries, addition of new ones,
and creation of a new local variables section when necessary.

Emacs file variables adjustments are also inhibited if `enable-local-variables'
is nil.

Operations potentially causing edits include allout encryption routines.
For details, see `allout-toggle-current-subtree-encryption's docstring.

You can customize this variable.