Box plot remove 'trace 0'

I’ve used the extra tag in the hovertemplate for box plot but still trace 0 (secondary box) is appearing. Can someone tell why it is appearing and how to remove it?

The trace 0 box didn’t appear when I used the extra tag in the hovertemplate for bar charts. But it is appearing for box plots.

PS : The secondary box doesn’t appear when I hover over the outliers.