This is a mechanism implemented by Meta to encourage responses from end-users when businesses send them marketing messages. They aim to maximize message engagement, improve the user experience, and help WhatsApp users find business messaging more valuable and feel less like they receive too many business messages.

Meta may limit the number of marketing template messages a person receives from any business in a given period of time. The limit only applies to marketing template messages that would normally open a new marketing conversation. If a marketing conversation is already open between you and a WhatsApp user, you may send one additional marketing template message.

To receive any further marketing template messages, the end-user must first respond to any message. A response is regarded as a free-form chat or a quick-reply button selected by an end-user back to the business. Note that selecting a call-to-action button is not regarded as a response.

Coming soon: If a marketing template message is not delivered to a given user due to the limit, an error code of 131049 will be generated with the description “This message was not delivered to maintain a healthy ecosystem."

Also see Meta's documentation:

• Per-User Marketing Template Message Limits