>I think that once you have more than X customers, you don't really need OSS testers and bug-reporters that much – your customers will be the first ones to file a ticket if anything is wrong. And as we saw with CentOS Stream, OSS users are not generally keen to be beta-testers.

In this case the customers they're losing (as well as the devs, testers, reporters, etc) aren't end users but companies who have built software offerings on top of Terraform. That's the class of user principally impacted by the change to the license. OSS users aren't stoked about testing, but developers who build on top of Terraform in order to eat will submit bug reports and PRs all day.