About the image: The joke's on you, I install my flatpaks via the terminal.
I've started using flatpaks more after starting using Bazzite and I liked them more than I expected. As a dev, I still need my work tools to be native, but most of my other needs are well covered by flatpaks.
Tip: Flatseal is a great config manager for flatpaks' permissions.
I replaced Firefox system package with Flatpak because I think browser is the most used and vulnerable thing in my system. And the size seemed reasonable.
I did not replace Thunderbird because its size is almost 10 times.