They have stopped onboarding new accounts, but from what I can see they don't say anywhere that it is "deprecated" or that it will be shut down in any foreseeable future.
AWS are usually very good in keeping services/features for people already using them, but will stop allowing new users when they don't want to push a service.
I don't see anything official from AWS stating this. The other link mentions it will still get security fixes but no new features, but no indication of it ever being discontinued.
Is it possible that they simply are working on something new and want to minimize the migration at a later point? (I guess that is still technically deprecating CodeCommit if its something new, but its a difference).
That is something that AWS tends to be really good on. Maybe a bit uncommitted on smaller features of a product, but this is a weird middleground on an entire product basically that isn't really clear on what the future is.
It doesn't even say "At some point in the future CodeCommit will go away and we will give X amount of notice". Just, no new signups.