And here I am back! And my earphones too…
Sent back to the repair center 2 weeks ago, they are back and functional (for the moment). The repair order states a replacement of the defective earphone (in this case the left one) and, indeed, the one comes back to me with a tip of a different size (so don’t send your tips).
The software version is still v1.0.1.46, so no firmware downgrade.
And I’ll finish by specifying that I didn’t pay anything