Question:
What is this problem in the comment reply? The others were sent successfully and the others were blocked.
Answer:
This indicates that your page is being limited at how many messages you can send per day and happens if your page gets a lot of message per day.
Here's a reference for this error, for a similar case, reported to the Facebook team.
https://developers.facebook.com/support/bugs/1824750847679674/
Also, this is because you send a Message Broadcast outside the 24-hour window and the tag you used is not appropriate.
When using a message tag, there must be no promotional content and the message should be according to the type of tag you used.
Please read the Messenger Policy here → Platform Policy Overview - Messenger Platform (facebook.com)
To avoid receiving this error message, kindly change your Flow to send only 1 message on the first thread and to follow the Messenger policy.