It was set up tubeless, I had to use an older inner tube section in addition to rim tape to get it to seal. This started failing and when my tubeless tyre ripped I popped in a tube- this punctured around the base of the valve. ..twice.

Can a rim ‘fail’ around the rim hole? Any solutions?

My crests are pretty coroded around the valve hole.

I imagine that could cause puncyury issues if it goes to far?

Inspect the hole?
Is there damage or a bur etc in there?
Is the tape intact around the spokes near the valve?
What sort of hole in the tube? If the tube moves in the tyre (could be more likely in a tubeless setup depending on the sealant it could rip/tear.
Tried it with a proper tubeless valve?

Can a rim ‘fail’ around the rim hole? Any solutions?

Yes I had a pair of dt swiss that cracked in the middle of the rim. They had done a lot of miles to be fair..
Simple solution = new rim.

Presta valve with a knurled nut? Doing the nut up too tight?
I’ve had a valve fail there when being a bit over zealous with my tightening.