[hayst4ck]

The author claimed Netlify's own support agent said it was an L7 ddos and offered a 95% concession because it was a ddos.

There is no reason to question whether it was a ddos or not because, allegedly, both parties in this dispute already agree it was a ddos.

[rvnx]

Also, DDoS or not DDoS it's very reasonable to believe that an individual (or even a company) isn't ok for a 100K USD bill.

Billing amounts should go through quotas requests, so you can explicitly ask to be migrated to the upper level, but by default have an active safety net.