You are using a 3rd party plugin to show the Categories filter, but we are able to help with questions related to our theme only, so you need to contact the support of that plugin.
if you have this url param in your url and the page is not first -> then the sidebar is broken.
You may ask the plugin authors if they don’t make any changes in case that param is in URL.
Also, it could be useful for them to know that we check sidebar positions and many other things by setting query_var() that are official WordPress functions ->
So if they break or reset query vars then they should make it compatible because it is a very popular function that allows minimizing conditions all over the site. Once we set query var we can use it in many files.
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