Its centralized nature allows the government to directly issue currency to citizens at the whim of central banks
This obviously means that they can not offer the same level of autonomy or censorship resistance that bitcoin offers
The fact that its implementation can lead to potential surveillance and increase government control over finance is something to be worried about.
Considering the fact that bitcoin has earned an high level of trust, security and borderlessness from it user with an inherent monitory policy brings the big question;
Do we really need cbdc now?
One of the limiting factors for Bitcoin is the capacity of the network and even the total volume of bitcoin in existence. You could argue that Bitcoin itself suffers from a form of inflation, because every year a certain amount of coins will be lost for a whole variety of reasons, from dust left over in transactions to wallets lost by owners. This makes it hard to realistically fit all the transactions that even small countries need on to the existing blockchain at a reasonable level. Certain countries may choose to take on a CBDC project to experiment with creating a truly digital currency but need it in a more contained and sterile environment compared to the constant fluctuations you see on pre-existing crypto
Total volume of coins does not matter, nor has it ever mattered for purposes of a currency. As long as an individual coin can be adequately divided, the purchasing power each coin provides is what counts.
Whatever coins are lost along the way makes the coins that are already on the moveable more valuable. Bitcoin doesn't have a fixed value and so the fixed supply isn't a limiting principle.