There is an old thread on this topic but it seems to have Dropped Dead in June-2022.

I have 4 Displays 3 of which are 1920x1080 all Scaled @ 100% and 1 that is 3840x2160 and Scaled @ 200%.
Also running latest DisplayFusion.

When clicking on the Calendar on any Display Scaled @ 100% the Calendar Displays Correctly.
When cliking on the Calendar on the Display Scaled @ 200% I can see an outline for the Larger Calendar Display but only 1/4 of the Upper Left Corner Calendar is Visible, the Visible Portion is however at the Proper Scale of 200%.

As with some programs started from the DF Task Bars, you see a Quick Flash of the Program Display on the Main (Windows) Display and then the Program jumps to the active Display, this is also true for the Calendar.

Here is what I have noticed AND have Screen Captures of:
When Any Calendar Button is Clicked on the Displays Scaled at 100% they first Flash on Display 1 (Main) before opening on the Active Display. When Clicking the Calendar on the Display Scaled at 200% it also flashes on Display 1 (Main) however the Contents of the Calendar Pop-up ARE Scaled at 200% so it Does NOT ALL Fit in the Pop-up and what is Visible on the Display Scaled at 200% is Eactly what was able to Fit in the Pop-up on the Display 1 (Main). In my case, the Pop-up Displays 1/4 of the Caledar (Upper Left Quadrant) and that is all that is Visible on the 200% Scaled Display in the Upper Left Portion of the Outlined Properly Scaled Area of the Screen.

I am Tempted to Try the Scaling in Reverse, 3 Displays at 200% and 1 Display at 100% to see if the results are Reversed but I don't want to mess up my Fences or Shortcuts on my Main Display.

The Picture of Display 2 with this Outline I mentioned is a Dark Background so you may have to look a little harder to see the Outline, it is there though.

Also you can see the Clock Text on the Right of the Task Bar on Display 2 is Still Truncated.

(EDIT): I just Clicked on my Network Icon on the DF Task Bar of Display 2 200% Scale and found that it does the Exact Same Thing the Calendar Does. It must have something to do with the way DF Grabs it when it Flashes. Again, what Flashes in the Pop-up IS at the Correct Scale, it just Doesn't Fit in the Pop-up on the Main so that is All you Get on the 200% Scaled Display.
I think this may be an Issue with most things that Pop-up on the Main Display that way...

Just a thought:
Could DF Trigger those Pop-ups using the Scale of the Main Display, Grab it and Scale it back to what the Display Scale of the Calling DF Task Bar is at DF does have all the Display Scale info already.