What's Going on With This CRT

[Drafalske]

Hello all. New Member, first post. I'm starting my first TV restoration and have a question about the CRT. The TV is a '49 or '50 Cromwell M712A (a re-branded Tele-King 712). I bought it from the original owner's son, who had no idea when it was last used or why it was taken out of service, only that it had been "decades" and "couldn't remember if anything was wrong with it".
There seem to be no missing parts, however I do see some replaced components (a couple caps and resistors) and most of the tubes appear to be replacements. There are no obvious visible issues but apparently it was well used.
Anyhow, I'm questioning a missing area of the interior CRT coating near the high voltage lead. It looks deliberate; not the result of some failure. I've never seen this and wonder if it's OK. The CRT is a 12LP4 or 12LP4A (there is no part number on it). No other marks or tags on the CRT anywhere. Could this be a rebuilt CRT?

I do not have a CRT tester. I purchased one, just waiting on it to arrive.
I have not attempted to power up or even plug in the set yet.

Couple photos attached.

Thanks for any info.

Dave