Do these FW 21.0.0 apps work on a lower firmware? In other words, will the apps, sysmodules, overlays, etc. give me any grief on 20.5.0? I'm setting up a new switch that is on OFW < 21.0.0 with the goal of upgrading the emummc to 21.0.0. Do I need two sets of apps, or can I use the 21.0.0+ files for a setup that starts with 20.5.0?
What does this mean for downgrading and such? I imagine once I am on 21.0.0 and have all of the specific apps for it, I can't just go back to, say, 19.0.0 without having to re-configure my system and replace all of the applications that were made for a lower FW version. Am I thinking about this the wrong way?