Ninja
Thanks for your answer. The way via CSS is known to me, but not so clean for me.
There are other adjustments that I would like to make.
The developer team could also integrate one in the core as a standard.
The name of the button is missing from the trigger button and so Google Lighthouse always makes a deduction for accessibility.
div.t4-content-inner > div#t4-header > div.t4-navbar > span#triggerButton
<span id="triggerButton" class="btn js-offcanvas-trigger t4-offcanvas-toggle d-md-none c-button" data-offcanvas-trigger="off-canvas-right-push" role="button" aria-controls="off-canvas-right-push" aria-expanded="false">
You can insert the aria-label="menu-button-mobile" like this and then google is satisfied.
Thanks