Verification done with ubiquity 18.04.14.12 / partman-efi 71ubuntu2.2:
I've tried the various permutations of installing in BIOS mode, in UEFI mode, or with UEFI with CSM enabled. All work as appropriate: when installing in UEFI with or without CSM and no ESP is created, the user is prompted; in BIOS mode the user is never prompted.
All of the above work without prompting in automated partitioning, as expected.
Verification done with ubiquity 18.04.14.12 / partman-efi 71ubuntu2.2:
I've tried the various permutations of installing in BIOS mode, in UEFI mode, or with UEFI with CSM enabled. All work as appropriate: when installing in UEFI with or without CSM and no ESP is created, the user is prompted; in BIOS mode the user is never prompted.
All of the above work without prompting in automated partitioning, as expected.