Hello.
Please make this fix.
1) Please open this file ../wp-content/plugins/{Booking Calendar Folder}/inc/js/form-conditions.js

( you can check how to edit files in WordPress menu in this article https://wpbookingcalendar.com/faq/how-edit-file-in-wp-menu/ )

then find this code:

function check_condition_sections_in_bkform(date, bk_type){      

and replace it to this code:

/**
 * Get elemnt ID of Conditional SEASON section,  relative to  specific day or false
 *
 * @param string td_class  - day  in format: td_class = 11-23-2015
 * @param string bk_type   - ID of booking resources
 * @returns bool | string
 */
function wpbc_get_conditional_section_id_for_seasons( td_class, bk_type ){      //FixIn: 8.4.5.3

    var garbage_prefix = false;
    if (       (typeof (wpdev_bk_season_filter) !== 'undefined')
            && (typeof (wpdev_bk_season_filter[ td_class ]) !== 'undefined') ){

        jQuery.each( wpdev_bk_season_filter[ td_class ], function ( index, singleClassCSS ){

            // S E A S O N    F I L T E R    C O N D I T I O N S     - checking
            if ( singleClassCSS.indexOf("wpdevbk_season_") >= 0 ){      // wpdevbk_season_high_season

                // LOOP in the Garbage
                jQuery.each( jQuery('#booking_form_garbage'+bk_type + ' div') , function(index, conditionGarbageDIV){

                    // class="conditional_section_element_season-times  wpdevbk_season_high_season wpdevbk_optional_condition"
                    var garbageElement = jQuery('#'+conditionGarbageDIV.id);       // Get Garbage DIV as jQuery element

                    if ( garbageElement.hasClass(singleClassCSS) ){                // We found our season filter element       in garbage with CSS class of that SEASON
                        garbage_prefix = '#' + conditionGarbageDIV.id;                             // Return  ID of Garbage DIV element,  that  contain  specific SELECT time field
                        return ;
                    }
                });

                // Check in booking form - its required for situation, when we selected date,  and some conditional section  already in booking form.
                var booking_form_element = jQuery( '#booking_form_div' + bk_type + ' .wpdevbk_optional_condition');    // .conditional_section_element_weekday-condition.wpdevbk_optional_condition
                if ( booking_form_element.hasClass( singleClassCSS ) ) {

                    garbage_prefix = '#booking_form_div' + bk_type + ' .wpdevbk_optional_condition' ;
                    return ;
                }

            }
        });
    }
    return garbage_prefix;
}


// // Show / hide  Fields  in the booking form,
// depend from week day or season filter
function check_condition_sections_in_bkform(date, bk_type){          

2) Please open this file ../wp-content/plugins/{Booking Calendar Folder}/js/wpbc_times.js

( you can check how to edit files in WordPress menu in this article https://wpbookingcalendar.com/faq/how-edit-file-in-wp-menu/ )

then find this code:

		if( typeof( wpbc_get_conditional_section_id_for_weekday ) == 'function' ) {
			var conditional_field_element_id = wpbc_get_conditional_section_id_for_weekday( td_class, bk_type );
			if ( conditional_field_element_id !== false ) {
				time_slot_field_name  = conditional_field_element_id + ' ' + 'select[name="rangetime' + bk_type + '"]';
				time_slot_field_name2 = conditional_field_element_id + ' ' + 'select[name="rangetime' + bk_type + '[]"]';
			}
		}

and replace it to this code:

		if( typeof( wpbc_get_conditional_section_id_for_weekday ) == 'function' ) {
			var conditional_field_element_id = wpbc_get_conditional_section_id_for_weekday( td_class, bk_type );
			if ( conditional_field_element_id !== false ) {
				time_slot_field_name  = conditional_field_element_id + ' ' + 'select[name="rangetime' + bk_type + '"]';
				time_slot_field_name2 = conditional_field_element_id + ' ' + 'select[name="rangetime' + bk_type + '[]"]';
			}
		}

		// Get rangetime element from possible conditional Seasonal section                  //FixIn: 8.4.5.3
		if ( typeof(wpbc_get_conditional_section_id_for_seasons) == 'function' ){
			var conditional_field_element_id2 = wpbc_get_conditional_section_id_for_seasons( td_class, bk_type );

			if ( conditional_field_element_id2 !== false ){
				time_slot_field_name  = conditional_field_element_id2 + ' ' + 'select[name="rangetime' + bk_type + '"]';
				time_slot_field_name2 = conditional_field_element_id2 + ' ' + 'select[name="rangetime' + bk_type + '[]"]';
			}
		}

Please do not forget to clear browser cache before testing these changes.

This fix will be exist in next update 8.4.5.3 of Booking Calendar.

Disclaimer. Unfortunately we can not start, right now, some personal customization or custom development, because almost have no free time.
Check more about new features here https://wpbookingcalendar.com/faq/need-new-feature/
Thank you for understanding.
Please note, if you will modify the source code of the Booking Calendar, we will not guaranteed the correct work of plugin and do not support it.

Hello.
Yes, I have tested it. And it’s was working for me. Please make the fix carefully, and exactly as in description.
Kind Regards.

Hello.
Yes, the dates must become unavailable (without clock icon).
Kind Regards.