@fthx If you have both DEB and Snap of CUPS installed, your print environment is managed by the DEB, the Snap switches into the so-called proxy mode, working as a firewall for your DEB CUPS, so that applications installed from the Snap store cannot mess up your system’s CUPS.
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I installed Mantic from the new ISO Ubuntu 23.10 “Mantic Minotaur” - Daily amd64 (20230825)
with cups .deb and i’m still unable to install a printer with gnome-control-center.
Problem solved installing from: Ubuntu 23.10 “Mantic Minotaur” - Daily amd64 (20230904.2)
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I may have missed something: every time I remove CUPS snap, it comes back maybe one day or two after. What causes this?
Perhaps it likes you very much ? 
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The CUPS Snap is used by any user application Snap which has print functionality, like LibreOffice or the Chromium browser for example. These Snaps plug the cups interface and this interface is provided by the CUPS Snap. Therefore they install the CUPS Snap as a dependency (a so-called content provider Snap, the same mechanism as GNOME or KDE apps install the respective library content provider Snap for GNOME or KDE).
If you have a classic CUPS (in Ubuntu via DEB packages) installed, the auto-added CUPS Snap goes into proxy mode, to work as a firewall to protect your system’s CUPS against user application Snaps doing something nasty (messing up your CUPS queues, spying on print jobs of other users).
So do not worry about a CUPS Snap being installed on your system, it is not your daily-driver CUPS managing your printers.
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Ok! So why my lovely CUPS snap is allowed to be removed?
Maybe it’s a deb-based argument but I don’t understand here why I was allowed to remove CUPS snap since some of my snaps depend on it. Is that what you mean with “content provider” ?
snaps do not have hard dependencies, I could fork and create a cups-ogra snap with a shiny patched cups version inside that magically operates 10x faster… this snap would then be able to be switched out against tills official cups snap without your apps noticing… this concept is for example used in the steam snap where you can replace multiple Mesa versions with different optimizations by switching channels of the graphics-core22 snap that provides the graphics drivers through a content interface.
That removing the last remaining content provider does not at least spill a warning should indeed be treated as a bug though, you should file it…
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