WordPress 5.5 Update Breaks
How to fix JQuery Migrate issue
We have now come across a workaround that temporarily fixes your broken plugins in the WordPress dashboard. All you need to do is download and install the official WordPress plugin called, Enable jQuery Migrate Helper. You can download the Enable jQuery Migrate Helper plugin at https://wordpress.org/plugins/enable-jquery-migrate-helper/
Thankfully, installing the Enable jQuery Migrate Helper plugin worked for us and fixed the number of issues we were facing after updating to WordPress version 5.5 temporarily. While the creators of your theme or plugin are fixing problems with the deprecated code (we hope so!) and trying to put the current version of jQuery to work, you can benefit from the temporary workaround. Once you install this plugin you may see a warning notification in your admin panel.
If you are a developer and your plugin or theme has experienced issues in WordPress 5.5, use the Test jQuery Updates Test plugin. You can download the WP jQuery Update Test plugin at https://wordpress.org/plugins/wp-jquery-update-test/
In WordPress 5.5, images will be lazy-loaded by default, using the native HTML loading attribute. If this is creating issues, you can use this Disable Lazy Loading plugin temporarily for now. You can download the Disable Lazy Loading plugin at https://wordpress.org/plugins/disable-lazy-loading/
WordPress 5.5 updates is a success, nevertheless. The WordPress community was impressive they are doing research on each problem to figure them all out. There are some issues related to WordPress 5.5 that have possibly affected thousands of publishers. But those problems are fairly easy to fix once the cause is identified.