Well, this is really frustrating when Tiktok suddenly shadow bans a user who were passionately posting videos for a long time. This action will surely let them down and will kill their confidence.
According to TiktokAddicts Forum, a Tiktok Shadow Ban is a temporary ban that the app will assign to any account for a limited period of time. The reason might be anything from spamming to uploading n*de content. When you are banned in this model, you won't be able to get good exposure to your videos. Even if you post exceptionally well content, you won't receive good number of likes and comments unlike never before.
This should be frustrating for many of the users for sure. They never expected this to happen and that will let them down. They were trying to improve their fan base by using some abnormal means but suddenly all your hard work go in vein. I can imagine the situation but we cannot do anything in the case of shadow banning on Tiktok.
There is no enough information on Tiktok until when a shadow ban will last when assigned to an account or user. Therefore, we cannot say that whether it's a week, month or a year! It might depend on the seriousness of the offense that the user had made. For example, if you posted a n*de video on your account, you might get a shadow ban of more than one month because Tiktok is strict about this rule. You're lucky that your account is not permanently banned.
The website TiktokAddicts has a Shadow Ban Checker that you can use to check if you are shadow banned or not. This tool will check the account for any potential ban in the account. The real advantage of this tool is that, it will also help in removing the ban.
Know more about this here - https://tiktokaddicts.com/tiktok-shadow-ban-how-can-remove/