unexpected extensions listed in system status
A couple versions ago the concept of &quot;hidden&quot; extensions was introduced. The theory was it would allow for moving bits of code out of core and into extensions without anyone noticing any difference at first, and then at some point make them visible/optional. You'll find them in the civicrm_extensions database table and also in the ext folder in the root of your civicrm folder.
So technically those are all still officially part of core right now, just the code has been rearranged.