People are finding themselves mysterious disappeared from WhatsApp.

Over the last day or so, a number of people have reported across social media that they have been removed from the app – without any explanation.

Affected users only see a notification that their account has been blocked and is being reviewed by parent company Meta.

“Your account activity and device info is being checked to make sure it follows our Terms of Service,” the message reads. “We’ll notify you of the result typically within 24 hours.”

WhatsApp admitted that it does sometimes get the deletions “wrong” but they are necessary to keep the service being from abused.

The app’s terms allow it to ban users for a whole host of reasons. But in a help article, it points specifically to the example of account activity that involves “spam, scams or if it puts WhatsApp users’ safety at risk”.

It also says that it can temporarily ban users when they are using an unofficial version of the app or involved in “scraping”, which it defines as “automated extraction of information, both targeted and at scale, for any unpermitted purposes”. Users who are engaging in either of those behaviours may find themselves subject to a temporary ban, and are advised to stop doing so or be permanently banned.

When a WhatsApp account is banned, it is unable to send messages or to access chat history or backups. Those should become available again if the ban is turned over – but WhatsApp notes that any ban can only be appealed one time, at which point it will become permanent.

WhatsApp said it had restored accounts that had been wrongly suspended and that it would do so quickly. But it noted that the rules were important to keep other users secure on the app.

“We are always working to stay ahead of those trying to abuse our service and ban accounts to help keep other users safe,” a WhatsApp spokesperson told Techcrunch.

“Sometimes we get this wrong, and if we do, we try to fix it as quickly as possible to get people back to chatting. We’ve taken action to restore affected accounts.”

The problems came around the same time as a seemingly unconnected outage that left many users unable to send photos, videos or stickers.