Interfacing 3-5V power source with 3.3V SD-card
The nRF52840 module can be powered in high-voltage mode by a supply between 2.5V and 5V and internally down-regulate that

Nope. That regulator has 25mA maximum external output, SD card needs 100mA minimum in SPI mode.
The sd card operating voltage can down to about 2.7V - I recommend using an LDO with enable pin just for the card alone. Thus it can be switched off completely when not in use. I recommend 3.0V as output voltage.
The SD LDO output voltage and the NRF chip VDD voltage must match - the default 1V8 VDD level (when using REG0) would be waaay too low. See REGOUT0 in UICR.