No blanking nothing, I've gone online before with SX OS back in the day several times by accident on sysnand and never got banned funny enough, however one time on atmosphere was enough for my dated old console, can already tell from that sentence alone that it's going to tilt so many people, so trigger warning, mind you I have done a lot of shit with it, anything BUT pirating video games, so miss me with that shit if you believe I did that, no sigpatch garbo either.
I've ran custom OS's on it, streamed windows games on it, ran homebrew, almost every thing you can do with it when switch modding started. So again, dunno what happened, maybe just shit luck, it's extremely hard to pinpoint what did the ban when the switch has been excessively used for many years on emunand.
Custom osses like Android and Linux are 100% unable to ban you, since they don't touch the switches os partitions, unless you explicitly mount them and touch them yourself, so this can be rules out.
Most bans are also not instantly, so often there are days or even weeks in between getting flagged and getting banned. So this makes exact pinpointing of the cause also hard in most cases.
Especially since there are multiple things in the complex often suggested setup that can go wrong. Since even when both nands are clean, connecting to the internet by accident on the emunand, while normally going online in stock sysnand can result in a ban from the mismatch in the logs send to Nintendo.
For the same reason restoring a nand backup or clearing the logs can get one banned.
Another thing I often mention that get one banned very fast, is installing homebrew to the home menu. Running them very much flags the switches via the invalid titleid in the play history.
Some people also use game icon changers, which might not be safe, where people use a donor game, and then replace its icon and Metadata, while letting it boot homebrew. Some of this information might be send to nintendo too, resulting in mismatches between the real Metadata and what nintendo expects.
For quite a while even causing a fatal error from homebrew could cause a ban, but thats not the case anymore, because at some point atmosphere reimplemented the fatal system module. Now those logs are stored on the SD, and never send to nintendo.