What is IP canonicalization?
If your website loads by domain name address and IP address, search engines see these addresses as duplicate versions of the same page. So, this case is similar to appearance duplicate content in www / non-www and http / https versions. So canonicalization redirects your IP address to the hostname. It works for SEO needs. When your website IP address is canonicalized, it redirects to the main domain hosted. As you may know, the duplicate content found on your website can harm your search engine ranking, so you can set up the process of selecting the appropriate URL for your website. We talk about such variants:
To conclude, IP canonicalization prevents your website from duplicate content indexing.
How to avoid IP canonicalization?
You should set a redirect from IP address to the main domain name address. If you don`t know whether such redirect already exists, you can use IP canonicalization test from Sitechecker tool. It shows whether your domain redirects to a domain name you entered.