https://global-search.toolforge.org/?q=jquery.cookie&regex=1&namespaces=&title=Gadgets-definition

The jquery.cookie library will eventually be removed. It is replaced with mediawiki.cookie (see T271995). Using it will result in the following error in your JavaScript developer console:

This page is using the deprecated ResourceLoader module "jquery.cookie". Merged into "mediawiki.cookie", use that module instead (T271995)

Gadgets should be updated per the warning message.

This impacts 376 scripts (https://global-search.toolforge.org/?q=%5B%22%27%5Djquery%5C.cookie%5B%22%27%5D&regex=1&namespaces=&title=.*%5C.js)

and 71 Gadget definitions files:
https://global-search.toolforge.org/?q=jquery.cookie&regex=1&namespaces=&title=Gadgets-definition

The solution here should be a simple find and replace, replacing jquery.cookie with mediawiki.cookie.

We will run a script to automate this, with some risk, so it is recommended that gadget developers manually upgrade these themselves if they can.