The initial intervals for microsoft defender atp and 365 defender are hard coded to last 5 and 55 minutes respectively. There doesn't seem to be any constraints in the API documentation. I plan on creating a PR to fix this.
Ah, I see this is for the modules, not the integrations. You are right, they are hardcoded - x-pack/filebeat/module/microsoft/defender_atp/config/atp.yml
x-pack/filebeat/module/microsoft/m365_defender/config/defender.yml
I also see your PR [Filebeat] Add Initial Interval for Microsoft Filesets by DumbBoi · Pull Request #42309 · elastic/beats · GitHub
I will make sure it gets reviewed. I would still strongly recommend using out integrations, which have better support, and are easier for users to maintain.