Use const char* because it's not altered past that point.

Marlin/src/lcd/extui/knutwurst/anycubic_touchscreen.cpp

@@ -983,7 +983,7 @@ void AnycubicTouchscreenClass::RenderCurrentFolder(uint16_t selectedNumber) {
       */
 
       // The longname may not be filed, so we use the built-in fallback here.
-      char* fileName  = strdup(currentFileList.filename());
+      const char* fileName  = currentFileList.filename();
       int fileNameLen = strlen(fileName);
       bool fileNameWasCut = false;