Messenger: unable to delete for everyone

Hello

A contact hasn't blocked me, but has probably restricted or filtered me or deleted the conversation on their end...

I can no longer delete a message for everyone in this conversation, whether it's an old message they read or a new message that has been sent but not received for a week.

I only have access to the option to delete for myself.

I know they are still connected and active otherwise.

So what is the reason for this impossibility?

Thank you