Are you sure about this? Because modem assigning dynamic range of IP address are designed to used like that unless you configure to have it as static assigning which probably coinbase knows a lot about it. Unless a VPN, new device or new browser is used and it will trigger their system.
Though disabling the account looks like not normal to me for every suspicious login, except when changing email or password.
Maybe on other countries gives only one IP per house but here in my country even its assigned in dynamic range or DHCP mode the IP change if you turn off and on the modem atleast on my case it changed.
It always happen to me everytime I change password or use other device it start since 2019 I guess.