The file gets created by Task 601 “List enabled modules to file using RHSM Download plugin - RHEL 8 - x86_64 (Prerequisite).bes” in the “Patches for RHEL 8” site
I’ll ask the patch team to advise, as I’m not intimately familiar with this, but it appears to be checking whether Modules are enabled for any given product (Modules basically behave to group RPM packages together into a single baseline, that must all be upgraded together, while isolating the Module/group from other RPM packages on the system). I don’t think Modules can be detected with built-in inspectors, hence the need to run some ‘dnf’ commands periodically to report on them.
This is new to RHEL 8, there was no Module functional in RHEL 7 and earlier, as far as I recall. A very large number of the RHEL 8 fixlets rely on Module patching and include the relevance that checks for the Module_cmd_output.txt, so if you’ll need to run that task on your RHEL 8 systems to get a clear picture of what updates are applicable.