The IP address you're seeing (starting with 100.96...) could be a static IP address assigned by your Internet Service Provider (ISP) to a specific device. A static IP address is an IP address that is manually configured for a device and does not change over time, unlike dynamic IP addresses (192.168...) which can change each time a device connects to the network.
Static IP addresses are often used for specific purposes, such as hosting a website, running a server, or providing remote access to a device. If a device on your network has a static IP address, it means that the IP address is reserved for that specific device and will not change, even if the device disconnects and reconnects to the network.
If you're unsure about the IP address and its assignment, it's a good idea to contact your ISP to confirm whether they have assigned a static IP address to any of your devices and to understand the reason behind it.
Private IP address ranges, like the familiar 192.168..., 10..., and 172.16... ranges, are used for devices within local networks (such as your home network). These addresses are not directly routable on the internet and are used for internal communication within a network. Devices with private IP addresses typically share a single public IP address through Network Address Translation (NAT) when they access the internet.
If you're seeing a device with an IP address starting with 100.96..., it's possible that this device is not connected to your personal mobile hotspot but rather has its own connection to the internet via a different means, or it might be using a public IP assigned by your ISP. If you're unsure about the origin of this device, you might want to check your network settings or consult with your ISP to get more information.