The plugin must be placed in the correct relative path: <app_dir>/platforms/qwindows.dll (Windows) or <app_dir>/platforms/libqxcb.so (Linux).
Repacking Qt platform plugins offers several benefits, including:
Alex had just finished building a sleek image-processing tool using Qt 6. The app worked perfectly on their Linux machine. But when they tried to run it on a fresh Windows test laptop, disaster struck: