Cassette "surprise" meaning replace chain relpace cassette

In 90% of my riding I use the second biggest ring on my rear cassette.
As the chain wore out I obliged, payed $35 and bought a replacement.
With a new chain installed I went for a ride and the "teeth" slipped under load, very very annoying.
I spent some time tweaking shifting tension, shifting is great!
Key idea: I tried to climb using a different ring on the rear cassette, no skipping!

After 30 min of troubleshooting it occurred to me that I may have worn just one ring, the one that I use all the time on Bridal Path.

I stopped blaming rear derailleur, derailleur hanger, cage alignment (the potential absence of thereof) who knows what else... It is possible to destroy one single ring in a multi-speed cassette, what a bummer!