Where is that? I'm pretty sure in France you can't just walk into a pharmacy and buy it, you need a prescription.
This sounds pretty much like the supply is somewhat limited for whatever reason.
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[0] https://www.ameli.fr/pharmacien/actualites/antidiabetiques-a...
There were previously supply issues with these drugs throughout Europe, but those were mostly resolved by the end of 2024.
By mid-2025, it was (and still is) possible to easily get all of the medicines for any of the approved uses, including weight loss and diabetes.