Environment CRC mismatch

[Floyd Brown]

The CRC generated by mkenvimage is not valid when written to the
storage device where uboot wants it.
I get a "Loading Environment from MMC... *** Warning - bad CRC, using
default environment" when I insert a SD card with U-boot and the
environment I built.

The environment is stored at the correct place on the SD card, I boot
U-boot and get the error, perform a "saveenv" and then read back the
saved environment from the SD card on my PC.
They look the same (uboot adds a serial number and MAC addresses when
the default is saved).

So the question then is, Do mkenvimage and the uboot build process use
different crc algorithms?

U-boot version 2020.04