It is one of the most dire aspects of Star Trek Picard: a long-running ban (under "galactic treaty") that eliminates not only research into synthetic life, but appears to ban synthetic lifeforms themselves.
And, candidly, I don't think it's an element of the story that is plainly justified on first read. It appears incredibly -- to the point of being implausibly -- reactionary, to an extent that we haven't seen from the Federation before. It also stretches credulity that a single event -- no matter how catastrophic -- could lead to such a long-lasting draconian policy. For it to be believable, we really need to assume that the Federation already was morally corrupt and weak-willed in a way that makes it in turn seem hard to believe that people of good character like Picard could hold the Federation in such high esteem. (Of course, there is ample evidence that the Federation, or at least Starfleet, has been immoral in this area for quite some time.) This is worsened, of course, by the sudden turnaround at the season's end wherein the ban is lifted, with apparently very little effort.
It's a weakness of storytelling in PIC S1. But, when we start to layer in stories from other series, a new picture emerges.
Let's work backwards. From PIC, we know what happens in 2385:
2385: in the Attack on Mars, rogue synths surreptitiously hijacked by the Romulan anti-AI extremist group known as the “Zhat Vash” lead a devastating attack on Mars, destroying the colonies, the Utopia Planitia shipyards, and the Romulan Rescue armada. Romulan involvement remains unknown for years after.
2385: a political crisis erupts following the Attack on Mars, with at least fourteen Federation members threatening secession. Starfleet chooses to abandon the evacuation mission, and Admiral Picard resigns in protest. Soon thereafter, a wide-ranging interstellar treaty – signed by so many powers that it was sometimes described as a “galactic treaty” – bans research, construction, and even the mere presence of synthetic lifeforms. Dr. Bruce Maddox flees the Federation shortly after and settles on Coppelius with Altan Soong.
Prior to that, PRO tells us about 2382-2384ish:
2382 (speculative): the Protostar launches under the command of Captain Chakotay, an experimental vessel equipped with a new propulsion technology called “proto-warp”, on a mission to return to the Delta Quadrant.
(PRO seems intentionally vague on the exact timing of this launch; potentially it could be placed as far back as 2378, or even maybe as late as 2384.)
2383 (speculative): Construction of the Romulan Rescue armada at Utopia Planitia is underway.
(The timing of the fleet construction is vague, but I argue it needs to be early enough such that the attack in 2385 creates a setback too large to recover from. As I recall, PIC is a little unclear on whether it would have been feasible to rebuild the fleet in time after the attack. But for there to be such severe political blowback, I think the project needed to have been underway for at least a couple of years.)
2383: following temporal displacement, the Protostar is discovered and commandeered by Dal R’El and his crew.
2384: the Dauntless, under the command of Vice Admiral Janeway and equipped with a (limited) quantum slipstream drive, embarks on a search for Captain Chakotay and the Protostar.
2384: the Battle of the Living Construct wreaks a heavy toll on the gathered Starfleet armada, which includes the starships Defiant, Centaur, Sovereign, and possibly Enterprise, as a viral AI hijacks starships via communication transmission and pits them against one another. The crew of the Protostar destroy the ship to terminate the signal and end the battle.
2384: full production of the Protostar class commences
There are two things to highlight here. First, this now marks the second instance of a destructive AI within as many years. It's unclear from PRO's finale how many ships are destroyed, but it is eerily reminiscent of the Attack on Mars a year later.
Second, the early 2380s saw the release of not one but two experimental FTL technologies, to say nothing of the use of sentient holograms as crew members. And yet none of that seems present by PIC S3 -- perhaps an illustration of the profound impact of the destruction of Utopia Planitia (and the all-but-certain brain drain as thousands of Starfleet designers perished).
Finally, we come to LDS' contribution to the tale of the early 2380s:
2381: the Battle of the Texas Trio, in which three autonomous Texas-class starships go rogue due to the malfunction of the AI known as “Badgey”. Before being stopped by a fleet of California-class starships, the “Texas Trio” carried out a devastating attack with significant loss of life, including that of Vice Admiral Buenamigo, who led the development of the Texas class.
That marks three rogue AI catastrophes in four years, with consecutively higher costs each time, culminating in what appears to be the destruction of an entire generation of technology development and Starfleet researchers, whose loss still appears apparent fifteen years later.
The Synth Ban wasn't just a reaction to the Attack on Mars -- it was a reaction to half a decade of AI disasters. No doubt the Ban was encouraged both explicitly and implicitly by Romulan (and Zhat Vash) elements, and even within this broader context, the Ban is still an overreaction. But the Attack on Mars "struck while the iron was hot", at a time when the Federation populace would be more anti-AI than at any point in history.
As a topic for a separate post, but the more I look at the pre-2385 vs post-2385 stories, the more stark a shift I see, and the more potential for potent storytelling becomes apparent. The Attack on Mars and the Romulan Supernova became a generation-defining event: the 9/11 of its time, separating the 90s-esque optimism of TNG, LDS, and PRO, from the 2000s-2010s-esque troubled times of the Synth Ban and PIC.