Daine
Google state clearly in Google Search Console (GSC) help that they record data (think links, traffic, errors) ONLY for the property variation added in GSC.
So, according to that document, regardless of redirects, when they collect link data, if someone has linked to the www version of your site, but your site resolves to the non-www version, then that link data won't be attributed to the property set in GSC, if that property is the non-www version.
If you add all 4 properties to a property set, Google will then aggregate that data.
If you add all 4 properties and you notice anomalies or errors for one of them, then you know there's an issue with the setup. If you had not added those properties, you may never have known there was an issue. Another good reason to add all 4.
Furthermore, sites often serve mixed content, https and http.
Now, when you look at search queries and link data (internal/external), if Google ONLY records data for any given property variation, as they state, again, this will not be recorded.
From Google themselves:
"If you are seeing no data for the site www.example.com, it may be because you have added your site using http://example.com To Google, these are entirely different sites. If you feel like you're missing some data, add both the www and the non-www version of your domain to your Search Console account. Take a look at the data for both sites."
As you can see, this is the exact reason why you should add ALL variations, and Google clearly advise this.
Not to mention that they advise to add all properties you 'support'.
As I say, support means all sites that are supported by your server (DNS and server config), regardless of redirects.
Clearly, people misunderstand the difference between server redirects and how Google collects data in Google Search Console (GSC).
Lastly, with respect to indexation, if you do a site: search for each variation, you may see different indexation results.
One of the reasons you set a preferred version, but as Google clearly state, redirects (301, or other) are to 'let everyone else know' what your preferred version is, not GSC.
"You can tell us whether you prefer for your site to be indexed with or without the www by setting your preferred domain. You can also let everyone else know which version you prefer by doing a site-wide 301 redirect."
EXAMPLE.COM
Example Domain
Example Domain

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Daine
Also, as far as I understand it, it has nothing to do with the final destination a visitor lands on, but what indexed version they come from via search.
They state in Google Search Console (GSC) help that they ONLY record data for the version added to GSC. They explicitly say this. So, if that version isn't added to GSC they won't record data for it and they certainly won't attribute any data to another variation.
Again, in their search console checklist, Google state that you should add both www and non-www to search console. Explicitly.
https://support.google.com/webmasters/answer/6332964
"Be sure to add all variations of your site root URL, including www and non-www versions, and all subdomain variations (example.com, m.example.com, pets.example.com). When you add your site to Search Console, we refer to it as a property. That's because Search Console supports both websites and apps."
Now, what about what you 'support'.
"If your site supports multiple protocols (http:// and https://), you must add each as a separate site. Similarly, if you support multiple domains (for example example.com, m.example.com, and www.example.com) you must add each one as a separate site."
That quote all depends on what the definition of 'support' is. As I understand it, this relates to your Domain Name System (DNS) and server configuration.
If people can access your site via www but then it redirects to non-www, you are supporting both versions, regardless of whether one redirects to the other.
Not supporting www would mean that your server is NOT configured with a DNS record for that sub domain and resolves nothing.
SUPPORT.GOOGLE.COM
Get your website on Search Console – Search Console Help
Daine
"Search Console reports the original URL for a landing page, even when that URL redirects to another page, for example:"
Costa
[funny image]

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John
What's the point of being in a group, when every comment is inbox me. Are there secretive information that needs to be private? 😂🙃🤡 _{👍🏽💟🤭10}

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Zee
I know this isn't helpful, but how did you even get a website without www. In front?
The only way I know of to do this is to setup a subdomain; that based off your basic www. Website. _{👍🏽🤭2}

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Rashid » Jabran
you have to submit http, https, www and without www to configure your domain and have the google to crawl all versions of your site and index it properly _👍🏽2

Soni
www and non www are treated separate URLs by google, you will have to upload everything again even your robots also SEO done on sub domain is completely separate _{👍🏽💟3}

Mew ^👑
Hey bud,
I’m curious why you’re interested in changing if?
Google has no preference over www or non www, so I am wondering what has prompted you to wanting to change it? _👍🏽3

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