As a workaround I have replaced grubx64.efi on the ESP with the one extracted from Debian sid's grub-efi-amd64-bin_2.12-1_amd64.deb which has my system booting again. I tried with the proposed package from Ubuntu 24.04 first but that did not work.
As a workaround I have replaced grubx64.efi on the ESP with the one extracted from Debian sid's grub-efi- amd64-bin_ 2.12-1_ amd64.deb which has my system booting again. I tried with the proposed package from Ubuntu 24.04 first but that did not work.