Git is still a DVCS, even today it's not being used in the way it was designed to be used by Linus and co.
The key distinguishing characteristic is the fact that every git checkout contains the full repo history and metadata. This means a consistent network connection to the master server isn't necessary. In fact, it means that the concept of a "master server" itself isn't necessary. With Git, you only need to connect to other servers when you pull down changes or when you want to push them back up to the remote repository. You can happily commit, branch, revert, check out older revisions, etc. on just your local checkout without needing to care about what's going on with the remote server. Even if you treat your remote repo on GitHub as your "master", it's still a far cry from the way that centralized VCS works.
If you've never worked with true centralized VCS, it's easy to take this for granted. Working offline with a system like Perforce or SVN is technically possible but considerably more involved, and most people avoid doing it because it puts you far off of the beaten path of how those systems are typically used. It basically involves you having to run a local server for a while, and then later painfully merging/reconciling your changes with the master. It's far more tedious than doing the equivalent work in Git.
Now, it's important to note that Git's notion of "every checkout contains all the repo data" doesn't work well if the repo contents become too large. It's for that reason that things like sparse checkouts, git-lfs, and VFS for Git exist. These sorts of extensions do turn Git into something of a hybrid VCS system, in between a true centralized and a true decentralized system.
If you want to understand more, here's a great tech talk by Linus himself from 2007. It's of note because in 2007 DVCS was very new on the scene, and basically everyone at the time was using centralized VCS like SVN, CVS, Perforce, ClearCase, etc.
Having been on call 24/7 for production services, I found "git log" absolutely essential, almost more so than the latest code. We were usually expected to roll back rather than take additional risk fixing forward on outages, so the question was "roll back to what?"
The key distinguishing characteristic is the fact that every git checkout contains the full repo history and metadata. This means a consistent network connection to the master server isn't necessary. In fact, it means that the concept of a "master server" itself isn't necessary. With Git, you only need to connect to other servers when you pull down changes or when you want to push them back up to the remote repository. You can happily commit, branch, revert, check out older revisions, etc. on just your local checkout without needing to care about what's going on with the remote server. Even if you treat your remote repo on GitHub as your "master", it's still a far cry from the way that centralized VCS works.
If you've never worked with true centralized VCS, it's easy to take this for granted. Working offline with a system like Perforce or SVN is technically possible but considerably more involved, and most people avoid doing it because it puts you far off of the beaten path of how those systems are typically used. It basically involves you having to run a local server for a while, and then later painfully merging/reconciling your changes with the master. It's far more tedious than doing the equivalent work in Git.
Now, it's important to note that Git's notion of "every checkout contains all the repo data" doesn't work well if the repo contents become too large. It's for that reason that things like sparse checkouts, git-lfs, and VFS for Git exist. These sorts of extensions do turn Git into something of a hybrid VCS system, in between a true centralized and a true decentralized system.
If you want to understand more, here's a great tech talk by Linus himself from 2007. It's of note because in 2007 DVCS was very new on the scene, and basically everyone at the time was using centralized VCS like SVN, CVS, Perforce, ClearCase, etc.
https://www.youtube.com/watch?v=MjIPv8a0hU8