This hasn’t been the case in decades, every OS defaults to randomly generating the trailing 64 bits of your address and cycling through new addresses periodically. Your IPv6 address is only fixed to your device if you choose to configure it that way.

Since the network half (leading 64 bits) is as fixed as your IPv4 address was, and the host half is random and constantly changing, an IPv6 address is exactly as uniquely identifying as an IPv4 address used to be.