I'm using Plasma with hiDPI displays, so I have fractional scaling turned on.

When fractional scaling is on, plasma-workspace sets environment variable QT_SCREEN_SCALE_FACTORS. For some reason this variable causes strange rendering issues with Telegram, MegaSync and some other QT applications.

The only way to remove this variable is to patch startplasma-x11.cpp:

```
diff --color -ru a/startkde/startplasma-x11.cpp b/startkde/startplasma-x11.cpp
--- a/startkde/startplasma-x11.cpp	2022-08-23 17:55:27.827687762 +0100
+++ b/startkde/startplasma-x11.cpp	2022-08-23 17:56:11.170498094 +0100
@@ -48,7 +48,7 @@
         KConfigGroup kscreenGroup = cfg.group("KScreen");
         const auto screenScaleFactors = kscreenGroup.readEntry("ScreenScaleFactors", QByteArray());
         if (!screenScaleFactors.isEmpty()) {
-            qputenv("QT_SCREEN_SCALE_FACTORS", screenScaleFactors);
+            // qputenv("QT_SCREEN_SCALE_FACTORS", screenScaleFactors);
         }
```

I haven't noticed any rendering issues with this variable unset, only improvements.