(short on time, so here's an overview to answer part of the question)
All password managers that are worth their salt (cryptography pun intended) have to anchor their trust to something, be it the OS's secret-storing APIs or a piece of hardware like a TPM (typically built into your machine's motherboard), an HSM (eg Yubikey) device, or an external source of authentication outright (eg a smart card, akin to what the USA Military does). Without any sort of trust anchor, a password manager is little else than a random program that happens to invoke a few cryptographic algorithms. It would be almost trivial for a malicious actor to use a bog-standard debugger like GDB to read the program's memory and steal the secrets, either after it has been conveniently decrypted by the program or by spying on the program while it performs the cryptographic algorithms.
Since a password manager runs within an OS, meaning that you already have to trust that your OS isn't an NSA backdoor, it makes sense to rely on the OS for storage of secrets. What the password manager does is provide the frontend for adding/updating secrets from the OS's store, while also making sure to authenticate the user prior to allowing access to the store of secrets. Once again, this is where hardware modules can come into play, but it can also be done using a main password. That is, you need to unlock the password manager before the secrets it contains are available for use.
Rather conveniently, the OS can also provide this authentication functionality: if you have already successfully logged into the computer, then that's a form of authentication. The most basic-but-reasonably-secure password manager would use two APIs to offload the difficulty tasks to the OS: the authentication API and the secrets API. That's the absolute bare minimum.
What Firefox's password manager provides, by default, is exactly that. But you can choose to upgrade to a Firefox-specific main password, so that if you forget to lock the computer, someone can't just open Firefox and use your secrets. This is one step above the minimum for a reasonably secure password manager, but it comes with the inconvenience of having to unlock the password manager every time you want to use a secret.
By and large, all password managers make these types of tradeoffs between convenience and additional layers of protection against certain threats. If your machine is inside the vault of Fort Knox and is actively guarded by people with machine guns and a keycard bullet proof door, then Firefox password manager is plenty acceptable.
Whereas a shared home computer in a situation where the disclosure of the secrets would cause a grave problem -- eg if an irate person finds that their spouse has a login for the local family court's online website, which might suggest a forthcoming divorce proceeding -- this might make sense to add additional layers. Indeed, some password managers can provide a decoy set of secrets, as a way of forming plausible deniability. If your situation needs plausible deniability, then Firefox's built-in password manager might not fit the bill.
I want to stress that using any password manager at all is already a massive improvement in security posture, and that any additional features and frills are merely refinements. Some folks are in high-risk situations where they cannot accept the possibility of off-device secrets synchronization, which would rule out Firefox password manager. But if you don't have such requirements, and if you can trust your OS, then you can also trust Firefox to store and manage secrets.
I have a rule which is that when anyone asserts that something is "more secure" or "more performant", they need to come with specific evidence for those claims. IMO, those two phrases are often used to "handwave" away any criticism for the asserted position, as a form of thought-termination. I would suggest that you always ask "more secure from what threat?" in response to such empty assertions. If they answer you with a specific scenario, then you can assess for yourself if that even applies to you. If they cannot answer with specificity, then Hitchen's Razor should apply.
I was going to write about how an existing tax agency (the California FTB) is already aggressive at tracking down high-earning residents that leave the state -- whether in-fact or on-paper -- in order to collect precisely what the state is owed per the tax code. That is, the FTB already engages and challenges the precise amounts that these former residents write on their final California tax returns, with some more spectacular results being some incredibly detailed timelines for when someone finally stops being a resident in California, as defined in state law.
But then I noticed that because of California's proposed wealth tax (aka Billionaire Tax) on the November 2026 ballot, the SF Chronicle has already started a series of articles to answer the specific what-and-hows of the wealth tax. This is the first article, pertaining to enforcement, and it agrees that the FTB would be capable of pursuing any high-wealth individuals that the proposal would tax. https://www.sfchronicle.com/california/article/ca-billionaire-tax-mechanism-21330110.php
This proposed tax in California is written as a one-time tax, so the question of whether high-wealthy people could flee the state is nearly irrelevant, because either they're subject to the tax or they're beyond the reach of the US courts (eg Venus). Almost. The remaining questions are legal in nature, and don't really change how the tax would be pursued. Whether FTB simply hires a dedicated team or outsources to private investigators, the task is still straightforward: follow the money.
Unlike civil lawsuit plaintiffs, who have more limited means of chasing down a defendant's assets in order to get paid on a judgement, the California tax authorities enjoy the benefit of the subpoena power, that can be used to compel companies and banks to tell the tax authorities about where and how wealth is being held. It is, after all, a core power of a US state to administer a tax, especially when the tax is authorized directly from the sovereign power (ie the citizenry). Any other result would conflict with the very purpose of a republic: to unyieldingly serve the people.