Your IP (v4) address is not part of your personal data.
It would be if that IP address was a static one. But as there are only a limited amount of IP (v4) addresses available, your ISP will assign you a different one whenever they see a need to do so.
It is considered meta-data and can be used as evidence against you when the IP address is known and the time/data of when it was assigned to you. Without that information, it is circumstantial at best and has been used successfully in courts as a defense against accusations.
A court order has to be obeyed, by any company, anywhere. As you are allowed time to find resources to help you in your defense, the accuser is allowed resources to legally build their case. Without the defender knowing about that. Welcome to the society you have chosen to participate in.
Proton mail, by default, does not log even meta-data. But has to comply if ordered to do so. Proton mail did mention that they don't log your meta-data by default. If you the reader comprehend from that text that the government cannot touch you, you are dearly mistaken. Content of the messages send through Proton mail have not been compromised, so nothing more than meta-data is retrievable as evidence.
A similar thing happens when you use a VPN. Their texts read as those services make you anonymous on the internet. And they don't, as that is not how the basics of the TCP/IP protocols even work. Government can ask your ISP for the same meta-data and see when and how long you are connected to your VPN provider of choice. Then the government only needs to ask your VPN provider about the meta-data you are generating on their servers and that is already enough circumstantial evidence to make things stick, without having to know the exact content of what is communicated between you and the services you connect to.
All the re-assuring texts you are fed by any service that promises anonymity on the internet are worth almost naught. In that sense, you should be happy that IPv4 still exists. With IPv6 each device will get a static IP number and then your IP address is suddenly hard evidence in court. If you are up to no good on the internet, an IPv6 address will not be your friend. Sorry, was reminded about the joke: "What is the difference between a friend and a best friend?" "A friend helps you move, a best friend helps you move....bodies!" With that in mind, an IPv6 address won't even help you move. It would be more like the card in Monopoly: "Go directly to prison, do not cross start, do not collect funds."