Well, when jQuery is updated (planned for WordPress 5.6, this may change, but that’s the plan right now at least so let’s work off that), then that function will actually cause breakage to your site.
I could link you to information on updating the code manually, but that particular function, jQuery.browser
, has no replacement and has been completely removed (as it was unreliable), and you will need to find someone to help you write new code to tackle what it was used for, or find a replacement. If there’s other problems popping up though, a generalised how to can be seen in this blogpost https://clorith.net/updating-jquery-code-in-your-unmaintained-wordpress-plugin-or-theme/, do note that it is not in-depth at all, and you should preferably get official updates to your themes or plugins, or look to maintained replacements.
Not the best of news, I know, but I do feel it’s important to be upfront about these things ??
As the original poster has not followed up with any new issues, I’m going to mark this topic as resolved (to help keep tabs on what topics are still looking for answers).
Should you continue having issues, feel free to follow up though!