Wasn't expecting to be tagged here but ill answer.
So myself along with several other people have been playing online with
cheats and modding on animal crossing since its launch with no issues.
Like what was mentioned before if you have blatantly modified modified your map contents or items and have that available for people to view and report then ypu could recieve a ban but only a game ban not a switch ban.
But just straight up using your
cheats for bells or whatever or even save editing will not cause this.
The other thing that will immediately cause a ban is if you have ANY nsp/xci pirated content installed and your console connects online.
I've been using my custom firmware online for a few years already and own all my games.
Infact i actively use
cheats on peoples islands all the time. Look at all these ACNH streamers with treasure islands using the ram editing apps to keep the island perfect. They would be banned as it is editing the save data but alas they arent.
Unfortunately i cant speak to how you got console banned but ACNH is pretty much guaranteed to not be the case.
This is highly incorrect

dont listen to MasterJ. But yes any pirated content doesnt matter what it is even if its tinfoil nsp installed. Will cause you a console ban.
There is some games with which you can be banned for save editing but they cause game bans not console bans and ACNH isnt one of them (unless like i mentioned you get reported for having an illegal map).