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If it is the funduino shield, The NRF is always supplied with 3.3V.
The other NRF pins are 5V tolerant, so that should not be a problem.
I now own such a Funduino Joystick Shield V1.A and did some further tests.
The power supply for the NRF24L01+ only worked for transmission (2MHz 0dB),
even with a 10µF added to the power pins.
Adding an AMS1117 brought the NRF24L01+ to full operation.