Does Telegram delete messages in secret chats if you don't read them in time or click on them?

Last night, I was chatting with someone on Telegram in a secret chat (room). I fell asleep around 10 p.m. This morning, I had two pop-up messages from Telegram (from this secret chat) in my notification bar. I couldn't read what they were about in the preview, because secret messages don't display that information. It always just says "new message" or "you have a new message." These messages were sent around 11:30 p.m.

When I clicked on the pop-up this morning, I was redirected to Telegram, and the chat and messages weren't there. So I don't know what the person was trying to tell me.

Is it normal for even unread messages to be deleted in secret chats if you don't click on them within a certain period of time?

Did this person really send me more messages, or was my phone acting up? Or did the person delete the last two messages?