Compatibility with PHP 8.x

My site currently uses PHP 7.4, and updating PHP to 8.x crashes the site.
This is what support says:

The warnings in your server logs indicate that the plugin Query Multiple Taxonomies (specifically widget.php) is using code that is not fully compatible with PHP 8.x:

PHP Warning: Declaration of Taxonomy_Drill_Down_Widget::init($file) 
should be compatible with scbWidget::init($class, $file = '', $base = '') 
in /wp-content/plugins/query-multiple-taxonomies/widget.php on line 11

This type of compatibility issue is a common reason why updating PHP from 7.4 to 8.x can cause the site to crash. Essentially, some plugins or themes rely on older PHP syntax or function signatures that have changed in newer PHP versions.

Recommended next steps:
1. Contact your developer to review the plugin and your theme for PHP 8.x compatibility.
2. Update or replace plugins/themes that are not compatible with PHP 8.x.
3. Once the site is fully compatible, you can safely upgrade PHP to version 8.3 or higher.

Attempting to update PHP without resolving these compatibility issues may cause site crashes or unexpected behavior.

Is this a known issue? Do you have a fix? Thanks.