block on Line after message: what happens?

My understanding is that when someone is blocked on the LINE app, they can't tell if they're blocked or if you just haven't read their messages.

I received a message from someone I had forgotten to block. So... I didn't read the message, but I blocked them and then deleted the chat.

My question is what did the person see when I deleted the chat after blocking them? Does it just look like I didn't read the messages, or will they know I deleted the chat?

They won't know. Their message will just appear as "unread" indefinitely.

They won't know you deleted the chat.
But there's one way ppl can see if they are blocked or not.
I think it doesn't work with iphone but with android If you try to give someone stickers it always says ''the person already has this sticker'' and you never be able to give sticker when you are blocked.
You know it's impossible for somone to have all the stickers so if it keeps saying ''the person already has....'' to every single sticker you can guess you're blocked.
Some people know this trick.