you may only need to switch secure boot off, boot into RL then turn secure boot back on. I’m not sure exactly how secure boot works but the idea is to prevent non-authorized boot devices. Could be using a white list of some description? ahhh I’m already curious let me see what I dig up on secure boot…
Ha seems the answer may of been on this forum discovered through trial and error
How to enable secure boot on Rocky 8.5 - General - Rocky Linux Forum
It seems that secure boot has a set of keys it registers based on the current boot setup and there is someway to reset these keys but I don’t recall anything that simple in the Dell bios menus back in the day.
I hope this gives you more insight into the situation.