Thank you all for your ideas! The phone has been working well so far. I have run the hardware tests without encountering any apparent issues (although I am unsure what a few of those tests are about).
The only thing is that the screen isn’t always as responsive as on my previous phone. For instance, when typing on the keyboard, sometimes just touching with the point of the finger does not work; I need to press harder. But if any other finger is in contact with the phone’s outer frame, like when I hold it with the other hand, then it becomes perfectly responsive to the faintest touch. Same effect if USB a cable is connected. This is not very pleasant because I often place the phone on a support and operate it with one finger.
I have not found a setting to adjust touch sensitivity. I wonder whether I am encountering this known FP4 issue or whether my device is not working correctly. If it is a software issue, should I try upgrading to Android 15 (my device is suggesting the upgrade, but I have not clicked on it yet)?