The simplest explanation is that they don't give a flying flamingo about what you or I consider "improvements to products".
This report is an example.
There are several changes that modify CI behaviour, where the article gives no corresponding quality measurement.
They replaced type aware custom lint rules with AST-only static analysis. They don't say anything about what those new rules detect, didn't do old-vs-new rule comparison. They switched the TypeScript check from tsc to tsgo. Again, they are very proud of the performance improvement, but don't seem to care about diagnostic equivalence. The list goes on. They don't even report pass/fail agreement between the old and the new CI. They have 4x more tests, but no idea whether this big test suite works any better than the smaller old one, or even whether it works at all.