Why 2 different Task Manager icon in FCP X?

I think it’s always been like that. If you open the background task HUD you’ll see a separate process line for each file.

The dark gray progress circle was replaced with the bolder white progress recently. Can’t say I see the point in the change though it’s a little more obvious.

I agree that the display is misleading, but I think it’s resetting when a file completes. It would be better as you say if it displayed the whole process. I believe the same thing happens when you optimize or proxy on import. Perhaps if you change a selection in the HUD the display will change.

I haven't seen two different progress icons, but today I noticed while creating proxies that the progress icon was resetting after each proxy was completed. In other words, I never saw the progress icon clock wipe the entire 360 degrees to show progress toward completion of the entire proxy creation task, just 1 or 2 degrees and then it reset to 0 when moving to create the next proxy. Has it always been like this and I just now noticed? 10.15.7, 10.5.4, footage is from FX6.

This seems kinda broken to me. If it's supposed to show progress for each file separately, then it should show percentage complete of that file all the way to full circle when it's completed that file. Instead it looks like it shows, or starts to show, percentage complete of the entire task of creating many proxies, but only gets to 1 or 2 percent and then resets. Am I thinking about this incorrectly?

I have noticed this too, sometimes it shows in one way, sometimes another. So far I have not been able to determine any discerning reason for it.