Delphi 10.3 Rio contains some regression bugs in FireMonkey code and they cause problems with using FMX plugins.
FMX host + FMX plugin. at closing FMX host, the
External exception 87Aexception will be raised. logged as https://quality.embarcadero.com/browse/RSP-21817
VCL host + FMX plugin. at loading FMX plugin, the
Cannot create Direct3D device for 'TCustomCanvasD2D'exception will be raised. logged as https://quality.embarcadero.com/browse/RSP-21756