See https://bugreports.qt.io/browse/QTBUG-84037 (incorrectly closed as fixed in 5.15.1; only fixed in Qt 6.0)
Adapted from Arch Linux patch: https://git.io/JtJs8
Upstream-Status: Backport
--- src/plugins/assetimporters/assimp/assimp.pro.orig
+++ src/plugins/assetimporters/assimp/assimp.pro
@@ -10,7 +10,7 @@ QT_FOR_CONFIG += assetimporters-private
 include($$OUT_PWD/../qtassetimporters-config.pri)
 
 qtConfig(system-assimp):!if(cross_compile:host_build) {
-    QMAKE_USE_PRIVATE += assimp
+    QMAKE_USE_PRIVATE += quick3d-assimp
 } else {
     include(../../../3rdparty/assimp/assimp.pri)
 }