Try this:
add_filter( 'generate_off_canvas_toggle_output', function() {
$svg_icon = '';
if ( function_exists( 'generate_get_svg_icon' ) ) {
$svg_icon = generate_get_svg_icon( 'pro-menu-bars' );
}
return sprintf(
'<span class="menu-bar-item slideout-toggle hide-on-mobile %2$s"><a href="#" aria-label="Open Off-Canvas Panel">%1$s</a></span>',
$svg_icon,
$svg_icon ? 'has-svg-icon' : ''
);
} );
Then adjust the aria-label
if needed.
Let me know ๐