Rpi-4 bootloader or faulty usb3 port or..etc..etc

i have several USB sticks…well 2 mainly…that i use on my rpi i may not have programed the boot loader… to boot off either USB 3 port correctly… this may be my issue here…???

having said this i run Ubuntu 20.10…with mate desktop…
y because it is what i am most exp with out of all Linux distro`s
i used Ubuntu to program the boot loader …

my problem is that …m2 ssd via its m-2 sata to USB bridge will boot off either after modding the command line boot file …my 32 gig sandisk ultra USB drive will only boot off the upper port of the usb3 ports it has the same distro on it…