Short version:
Brave is really secure. Only risk is people who can access your OS profile/user account.
3rd party password manager: Higher vulnerability/risk but more convenient in a way. More preferable if you’re worried about people around you and not so much about accounts being hacked.
Same info, more detailed, kind of:
Brave: Saves locally and overall secure. Big “risk” is if you’re using shared device or have it somehwere that someone can physically access and log into your OS User profile/account. Passwords are encrypted using your OS login credentials, but otherwise no “master password” or anything. So if person can get into your profile, they can get your passwords. Also, if something goes wrong with browser (and it’s not synced), you lose it all.
3rd party password manager: Saves your information online. Usually they come with a master password, so if someone logs into your OS profile and opens your browser, they would have to put in a password or pin you created in order to login to websites. It also makes things more convenient because will exist even if things go wrong with your device, it’s backed up on the cloud. The negative is these accounts can be hacked. In fact, you can even see some more recent vulnerabilities. Examples:
-
https://www.pcmag.com/news/zero-trust-you-can-steal-passwords-from-keepass-with-this-free-app
-
https://www.pcmag.com/news/hackers-target-norton-password-manager-access-8000-user-accounts
Personally, I prefer trusting Brave. It’s harder for people to access and all I need to worry about is keeping my own physical device secured (including monitoring for potential keyloggers/malware/viruses). But if you need to worry about people who are around you than you than you do people around the world on the internet, then go for a 3rd party password manager.
NOTE
Regardless what you use, you’ll likely want to make sure you keep a backup of sorts in an offline location, such as on an external drive. This is especially true if you use Brave. Things can always go wrong and if you become 100% reliant on password managers, you could be crap out of luck if something happens and they are erased.