It is correct to display the message when appropriate, but this is supposed to happen only when there are associations for the item and the item language is modified while editing the item.

This means that the js is not working properly.

in the non-minified association-edit.js, we have
First

          if (!existsAssociations && document.getElementById("".concat(formControl, "_associations_").concat(languageCode, "_name")).value !== '') {
            existsAssociations = true;
          } 

and further

        }); // If associations existed, send a warning to the user

        if (existsAssociations) {
          Joomla.renderMessages({
            warning: [Joomla.JText._('JGLOBAL_ASSOCIATIONS_RESET_WARNING')]
          });

@dgrammatiko @Fedik

JavaScript are ok, the bug comes from the association field, it have a value="Select an Article" when nothing selected,
that is wrong of course

@Fedik
I see. It happens even if the item is set to All, which means the fields are not displayed.
There must be a solution.

@infograf768 you were right, it a script

please test #27269

Replied there. Will explain further tomorrow.
Please do not close this issue now.

Patch #27269 works fine.
Closing this.