First of all, Happy New Year.
I ran various tests. It seems that the decisive factor is the scaling. At 100%, the icon was always correct, regardless of whether one or two monitors were connected.

Thanks! More questions: do you need two monitors to reproduce the problem? Or does it happen with one only? Is scaling relevant? Or would the problem happen even with 100% scaling?

Yes, I use a Win11 PC with two connected AOC 4K office monitors, each with a scaling of 150%.
When I turn the monitors off and on again, the correct WinSCP icon almost always disappears (no Win+L necessary). This happens regardless of whether it was minimized, open, or active. I noticed that shortly after the image reappeared, WinSCP was not yet in the menu bar, but only appeared a second later, on the far right with the wrong icon.

Thanks for more details. So you have a desktop PC (not a laptop – no integrated display) with two external monitors? Does it matter on what monitor (primary/secondary) is WinSCP window located? Does it matter if WinSCP window is in the foreground/background/minimized?

Yes, that's it. I ran a few tests.

1. Win+L (Win 11) plus turn off both monitors.
   
2. Turn on monitors and log in.
   

WinSCP is now in the far right position in the menu bar (even if it was somewhere else before) and displays the default icon.

As you can imagine, this behavior is very difficult to observe directly. However, I think that yesterday evening the icon in the menu bar (rightmost icon, no “...") was still displayed correctly, but this morning it appeared as the default icon. Overnight, I lock Windows with Win+L and turn off the monitors. (But that's not the only way the icon gets lost.)

The icon reappears when you bring the application to the foreground and click on the passive side. This probably triggers a window refresh, which also displays the icon in the menu bar correctly again.

Thanks. Please let me know if you observe when the icon is lost.

I lost the correct icon several times. However, it also returned on its own. Unfortunately, I did not observe this live.

But now I was able to see it return. It was when I copied a file from the right (Linux) to the left (Windows) window by pressing F5. Something at the end of the copy process brought the icon back.

Ok, thanks. Please let me know.

Thanks for looking at this report.

First, the wrong icon was not only in the "…" menu of the taskbar, but also normally on the taskbar when I closed a few applications.

Anyway, I stopped and restarted WinSCP. Now the icon appears correctly in all locations. I briefly tried to reproduce the behavior described, but unfortunately (or fortunately?) without success. Maybe I will be able to observe the behavior again at some point and say more about it.

Thanks for your report. Though I cannot reproduce it. Does the wrong icon appear as soon as you start WinSCP? Or does it break only later? When?

I'm using WinSCP 6.5.3 under Win 11 [Version 10.0.26100.6584].

If my taskbar is full, a menu '…' appears at the right end of the taskbar. Clicking on it I see the open programs with the specific icon. But WinSCP use a standard icon. As you can see in the attached screenshot 7zip does it right (and all others too).

Well, it's not a bad thing, but definitely nice to have. ;-)