Investing into a department is not the same as stuffing more engineers into a team
Almost as simple as Quality > Quantity.
Investing could mean hiring more experienced candidates rather than more candidates. Investing could mean having a fraction of the devs and far more resources for each one of them. Whatever the problem this is absolutely a GitHub management issue they gotta fix.
But maybe hiring few more senior folks at higher salaries could help more than hiring twice as many juniors?