Delete button on UI

I was sure that the Delete button on the UI took the last event number, and did a truncate before.
Has this been changed?

I was clearing down a stream and hit delete. and my metadata looked like this:

“$tb”: 9223372036854775807

So does that mean everything gets truncated from here going forward?

Btw, for my particular issue, I just posted another metadata event indicated $tb for the value I expected it to be.