how to block messages from a sender with no number

I tried using the block feature in the Messages app, but it doesn’t work, the sender automatically gets unblocked. How do I solve this issue? I have recorded a video of the issue and uploaded it on YouTube for reference. The link to the same is provided below.

Link of the video showcasing the problem: https://youtube.com/shorts/ymQcGOp7rDg?si=7SXHy3R35vN9JB-o