IP Address Localization Issue

writing on a network ....
you have a profile on FB, I suppose you put where you live in it, so it's FB that makes the connection between your IP address and your city, you see?
however, a mobile can locate itself even without GPS, just with the information provided by the GSM network, even if you connect via Wi-Fi.
If you launch Google Maps even without GSM, you will be located on the map by Google and not by your IP address, because the address will indicate your ISP.
Geolocation by IP address is unreliable in most cases and especially with a mobile, by definition.

Indeed, on my FB profile, I put my place of residence.

But where it gets tricky is that, whether on laptop or iPhone, sometimes the location is, as I said earlier, 100 kilometers away from my home (and always in the same city 100 km away).
So the argument of the city-residence link on the FB profile no longer holds.

And there is undoubtedly a link with the IP address since the laptop follows the same location 100 kilometers away. I reboot the router and get a new IP address, and then, both on the laptop and the iPhone, the position returns to where I live.

This "bug" has happened several times, and as for the 3G with an IP search (they redirect to the ISP's address), I find it harder to understand the reasoning when it comes to the wifi IP address and therefore the one used by the laptop and the iPhone on wifi. And there’s nothing that connects me to that city. And if it’s an IP with a random location, why always the same city? Statistically, it doesn’t make sense.

So I see where you are going with your explanations, but the fact is that it does not match at all with what I observe. Since even Chrome sometimes locates me in that city 100 kilometers away. So it’s not just about FB or mobile usage but a faulty IP address indicating an incorrect location - but always the same place.

The city in question, isn't it the headquarters of your ISP?
Or that of the mobile operator?
In any case, it clearly shows that it's not reliable to use the IP address for that.

What difference does it make if it's the city of my ISP?

For searches with addresses obtained via mobile when I'm on 3G, it indeed redirects to the ISP's address

Not for Wi-Fi connections and it wouldn’t make sense to redirect once out of 30 to the ISP, would it? Are location services via Gmail, Chrome, FB, etc. just a scam? How can it be explained then that when I go abroad or even to the other end of the country, it locates me well via FB, Gmail, and Chrome in that case?

Is location services via Gmail, Chrome, FB, etc., just a scam?
Yes, that's what I've been saying from the start, at least not very reliable except for mobile location, and in any case not at all if the mobile doesn't want to be located.
Once again,
a mobile phone is permanently located by its operator.
Either the mobile broadcasts the information, if it's a smartphone, or it's the operator
When connected via Wi-Fi, it's the ISP of the access point we're connected to.