Programs ran through Flatpak can only access permissions and directories that it has explicit permission for. This is perfect for a very small program that only does one thing, it can get rather awkward when you need it to access multiple storage volumes. For example, I wanted to have my Steam games stored on different hard drives, but they were never visible through Steam. I had to override the Flatpak permission to give access to my mounted disks for it to work.

In what sense?

FPS counters in games usually display an average across multiple frames. That makes the number actually legible if the FPS fluctuates, but if it fluctuates really hard on a frame-by-frame, it might seem inaccurate. If I have a few frames here that were outputted at 20 FPS, and a few there that were at 70 FPS, the average of those would be 45 FPS. However, you could still very much tell that the framerate was either very low or very high, which would be perceived as stutter. Your aforementioned old games probably were frame-capped to 20, while still having lots of processing headroom to spare for more intensive scenes.

The real answer to the burning cables is to divide the wattage between the six wires on a single connector, which most of the 50-series cards don’t do that. That results in ~15 amps across a single scorching cable.

Or maybe it just delivers 600W without burning the ever-loving hell out of the connectors.