I'd say there are more pressing and fundamental issues to be addressed, such as connectivity issues, skills and skill nodes straight up not working, etc.
A simple dupe glitch should be the least of their worries right now.

Hello,

I can confirm this bug aswell. Came here to report it.

Following the how to 'report a bug' : I did not see the bug mentioned on Trello

Info:
I was in the town of Chapter 1. Had 2 crude copper fragments in a stack. Unstacking and stacking it incresaed it's gold value. Specifically 1 gem would have a higher value than the other (but both increased) and the bug only occurs when adding the lower value gem to the higher value gem and unstacking it (adding the higher value one to the lower one didn't do anything). Went over 500 milion and stopped there,don't know if there is a limit before it breaks. Tried selling the gems and this worked giving the full value (over 500 milion, aswell as the lower value one which was also in the 200 milion). Buying items also does not reset the gold. I did this in online mode in a private campaign with no other players in my session.

So do I delete my character? (Character name Lance)

P.S: My stash was empty on logging in while I still had items in there yesterday(after patch). Specifically Stash 1 (did not have any of the other tabs bought). During testing the bug i was able to add and remove items to the stash.

Can confirm too. Did it this morning to see if it actually worked.

Can we get a confirmation if deleting the char proactively is enough?

Also discovered this one on my own - shift-clicking stacked gems will copy the current value of the gem x the current amount in the stack into the value of the single gem copied out, you can then move the whole stack into the single stack to convert the entire pile to the newly multiplied value and repeat back and forth for infinite gold.

I tried it out minimally by only going up to 100k and I did receive the gold from the sale.