There's little difference in using "why turning on http/2 (is/was) a mistake". Is is stronger, but both imply that there is/was something wrong with it, to the

There's little difference in using "why turning on http/2 (is/was) a mistake". Is is stronger, but both imply that there is/was something wrong with it, to the point of writing an article about it. A better title would be "why turning on http/2 was a mistake (for us)." The current one implies failure due to http/2 itself, and not architectural decisions that lead to making the upgrade to http/2 not as easy as imagined.