Yes. It is unethical. Your duty is to your client, not to your public policy position, even if your political position is just and even if it would benefit other hypothetical clients in the future.
If we want to see change in the justice system we need wider societal education and to force that change from the outside, but that butts up against a lot of "hard on crime" rhetoric.
How can a public defender ethically represent a client when they have so little time to prepare for a case? If you have 30 cases at a time and minutes to spend with your client how can you do your job to the standard deserved by a defendant?
If the above isn't too difficult, then suspending plea deals shouldn't be much of a stretch?
For others, you can always request a continuance and make sure you put on the record that the current timeline will force you to be ineffective.
If your client were unaware of the strategy, would it be unethical to tell them?
So therefore it's unethical for a prosecutor to accept a plea deal less than all charges.
"In the interest of Justice" is a pretty thin excuse.
https://www.americanbar.org/groups/criminal_justice/standard...