Seems like I solved it for linux-toradex (but I have still check if it has some unwanted side effects).
Inspired by commit b97a88c0cb100e059673cbcc75ac79ef0eb24f39 in meta-toradex-nxp I added this line to my recipes-kernel/linux/linux-toradex_5.4-2.3.x.bbappend file:
# Remove AUTOINC from PV="5.4.193+gitAUTOINC+498c1d54ef"
PV ="${LINUX_VERSION}+git${@'${SRCPV}'.replace('AUTOINC+', '')}"
And to recipes-bsp/u-boot/u-boot-toradex_%.bbappend:
# Remove AUTOINC from PV="2020.07+gitAUTOINC+4baed78646"
PV = "2020.07+git${@'${SRCPV}'.replace('AUTOINC+', '')}"
I could not find out which variable defines 2020.07, but for now it will do.