Gmail and other huge centralized points of censorship and surveillance must be destroyed. If you are a user, move away. If you are a developer, do not support these closed systems.
This is a super common misapprehension people have about data locality and surveillance, and it's no surprise that marketing plays off it ("keep your mail in Switzerland, so it's subject to Switzerland's strict privacy laws!").
There are other reasons to house things in Switzerland (or the Lesser Antilles or wherever). I'm not saying you should use GMail (unless security is a concern of yours, in which case you should use GMail).
This is no longer true, as Ed Snowden showed us. This is literally the point of their secret interpretation of FAA702. Pretending otherwise is nonsensical. The USG, just like the CCP, gets whatever data they want, about anyone, from servers in their own country, without due process.
Anyway, my comment was not about jurisdiction, just about surveillance.
Regardless, Google obviously has the plaintext if you use Gmail. You don't want that, either. The USG will probably only use it for a subset of things; Google has no/few limitations on the use once you voluntarily give them such a huge trove of data about your life, travel, vendors, and purchases.
There's also the issue where Google itself is mass surveillance.
Secret services swap their data, so they can all read my santa letters.
There is the viewpoint that one should prefer one's own jurisdiction regarding storing data (I know you don't like Schneier but he e.g. holds that viewpoint).
I use an email provider from my country. If a judge from my country wants to persecute me, they have to complete a legal request which is tested by my provider.
If I used an email provider from Switzerland or the US, is that also the case?
Also, it's important to think of the economical aspect. If i financially support providers in my home country that lobby for better privacy laws and don't engage in surveillance capitalism like Google does, isn't that creating a good alternative that can also be properly regulated?
Plus, it's one dependency less from a (more than) half MAGA country.
So your recommendation makes sense if you are a citizen of the USA, but not everyone here is.
Addendum: what do you actually mean by "security"? For me, that is also "being able to access my email account whenever I want" and that this account doesn't get closed, even if I do shit on the internet, whoever that decides. Google shouldn't have the right to say "these actions are uncool so let's kick this guy" (never happened to me, but I don't even have a contract with Google!, they have the right to cancel my account whenever they want.).
This is not some principled stance, it is a clear and practical command: stop using these services.
If your personal email address ends in @gmail.com, you are doing it wrong.