Unverified Flatpaks are disabled by default. A warning explains the security risks associated with them in the newly added preferences window. https://www.phoronix.com/news/Linux-Mint-Unverified-Flatpaks As always at Phoronx, don't overlook the comments.
That was a good read. I am running 24.04 as a host and I am thinking about totally removing snap, but then comes flatpak and other sources. You can be careful and safe, especially if you gpg verify with good products. I wouldn't give flatpak a blank check though. I do applaud Mint for how they are proceeding. Wonder how many of their users will simply enable Flatpak anyway?
Probably most of them as that is now the "chosen path" of the dictatorial direction Mint is taking. And, as most of us are aware, convenience plays the biggest part in many of our decisions.