As always, "it depends" on the application. So I've worked for several B2B SaaS companies. None of them used a VM per tenant. In some cases, we used a database (schema...) or DB cluster per tenant.
I've read about the Vercel incident. Given the timeline (22 months?!), it sounds like they had other issues well beyond shared hosting.
I've read about the Vercel incident. Given the timeline (22 months?!), it sounds like they had other issues well beyond shared hosting.