diff -rupN --no-dereference qgis-3.18.1/src/core/qgsapplication.cpp qgis-3.18.1-new/src/core/qgsapplication.cpp
--- qgis-3.18.1/src/core/qgsapplication.cpp	2021-03-19 13:09:08.000000000 +0100
+++ qgis-3.18.1-new/src/core/qgsapplication.cpp	2021-03-24 00:58:46.103156947 +0100
@@ -311,6 +311,11 @@ void QgsApplication::init( QString profi
         {
           myDir.cdUp();
         }
+        // Fix for server which is one level deeper in /usr/libexec/qgis
+        else if ( applicationDirPath().contains( QStringLiteral( "libexec/qgis" ) ) )
+        {
+          myDir.cdUp();
+        }
         myDir.cdUp(); // Go from /usr/bin or /usr/lib (for server) to /usr
         QString myPrefix = myDir.absolutePath();
         setPrefixPath( myPrefix, true );