The problem with anchors on the site is due to the header plugin.

Hello. The problem with anchors on the site is due to the header plugin.
We wrote to the developers of the divi, that's what they answered.
Hi Evgeny!

Faisal here from the senior support team.

Issue is actually caused by a 3rd party plugin named "Divi Ultimate Header Plugin". You can contact their support/author later.

For the time being I have fixed the issue using this JS code that is added in:
Theme Options -> Integration -> "Head"

<script>
jQuery(function($) {
setTimeout(function() {
var windowsize =$(window).width();
//if (windowsize >= 980) {
window.et_pb_smooth_scroll = function( $target, $top_section, speed, easing ) {
var $window_width = $( window ).width();
$menu_offset = -1;
var headerHeight = 150;
if ( $ ('#wpadminbar').length ) {
$menu_offset += $( '#wpadminbar' ).outerHeight() + headerHeight;
} else {
$menu_offset += headerHeight;
}
//fix sidenav scroll to top
if ( $top_section ) {
$scroll_position = 0;
} else {
$scroll_position = $target.offset().top - $menu_offset;
}
// set swing (animate's scrollTop default) as default value
if( typeof easing === 'undefined' ){
easing = 'swing';
}
$( 'html, body' ).animate( { scrollTop : $scroll_position }, speed, easing );
}
//}
}, 100);
});
</script>
There is a value like 150 in this part of the code:

var headerHeight = 150;
Change its value a bit to your liking according to the height of the sticky (fixed) navigation bar.

And let me know if it works for you.