It is not clear where this user "C" came from and what he is responsible for. This user has permissions for all spaces. But it's not clear which application is using it.
Welcome to the community @Uladzislau Rachok
Each of the apps that has been installed to your space, automatically creates the user that will have the permissions in this case to Create spaces. The user C is indicating to an application that was installed from your end.
How many applications that start with C have you installed on your space?
We have such an application "Composition for Confluence". But I don’t even know what it is and whether it’s used.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.
I have found that application in here: https://marketplace.atlassian.com/apps/245/composition-tabs-for-confluence?tab=overview&hosting=cloud
Do you know who installed this application, if so, ask how many people are using it.
Another thing that you can do is to have a test instance of Confluence and install this application then compare if the user is actually the one that is showing from the screenshot.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.