I 100% agree that any interaction with the fediverse is public and this does not stop Meta from creating a minimal instance under a different domain which they probably already do. This act is one of protest.
TechnologyClassroom
Defederating or suspending will prevent your instance from seeing the content of another instance. Blocking the IP addresses associated with the domain will prevent the other instance from seeing your content by normal means. Meta could spin up a secret instance to spy on the fediverse (and probably already does this) which is impossible to stop, but this act is a means of protest.
You may be accustomed to the process, but fixing issues in the registry is not intuitive. It is simple enough if you find a guide that tells you exactly which item you need to work on and exactly what the default is and what you need to change it to, but what if the guide isn't exactly what you want?
In the GNU/Linux ecosystem, nearly every program has a config file. Sometimes each line has detailed comments in plain text around it you what the option does with examples of what it could be. If the documentation doesn't exist, you can dig deeper and see what that option does in the source which is usually documented as well. Programming experience is not required to search for text and read comments. Such documentation is not equivalent in Windows.
You cannot rename a file from webp to jpg, but you can change the URL to .jpg and it will likely serve you the jpeg version. You can also convert webp to another format with dwebp or MS Paint.