Due to the recent depreciation of the Yen, I believe many players are more active in buying Switch day games. Taobao and various online sales platforms have always had the opportunity to find very cheap download versions of the game. But as the old saying goes: "cheap is not greedy", buying these unexplained downloaded games may at any time lead to your Nintendo account being banned.
If you see a digital version of the game online that sells for an unreasonable price, or bundles several download codes, it is likely that it will come from the so-called "black card", that is, the stolen credit card. After obtaining the "black card", the criminals use it to buy a digital version of the game at the Nintendo eShop, and then put the exchange code on trading platforms such as Taobao and Mercari, so that the black card can be cashed out.
If the player buys these low-priced games cheaply, because these redemption codes are ultimately from the "black card", after the original card owner reports the loss or the bank check determines that it is an illegal transaction, Nintendo will not receive the payment in the end. In other words, Nintendo will treat these digital versions of games purchased with "black cards" as pirated games, and Nintendo accounts that use these redemption codes may be banned and can no longer be used.
There are two main types of bans at Nintendo, the most common of which is to restrict account access (ban accounts). Banned Nintendo accounts will not be able to use eShop, download games, and connect to the machine, but users will still be able to use the new Nintendo account on the Switch console. A more serious restriction is the ban of the host network (ban machine), and any account on the Switch host can no longer use any network functions.
The Switch host in both banned states can still connect to WiFi normally, but error messages such as "2124-4007" and "2124-4508" will appear when accessing eshop, online or updating games. Once the account/host is banned, even if the factory reset cannot be "unbanned".
If you don't want to "get caught", the only suggestion is to buy the digital version of the game only on the official eShop, so as not to lose a big deal. Don't think that as long as you don't buy download codes on Taobao, there is no problem, the same large Japanese second-hand trading platform "Mercari" is also a hotbed for such "black card redemption codes", so recently Mercari decided to stop all digital versions of the game and in-game virtual props and other goods on the shelves.