Issue with SendMass requests, returns FLOOD_BLOCKED. What is the problem?

Question

Classmates

Good afternoon. I am making a notification daemon for a game application on the OK site. To be more precise, I just use the old one from the previous application. When making requests, SendMass gives a FLOOD_BLOCKED error, what exactly does this error mean? Too frequent requests, or exceeded the limit on the number of requests per day? (Judging by the application panel, it has not yet been exceeded)
Moreover, in the old application, a similar server with the same settings works without problems