This appears to be the initial complaint, from 2018: https://regmedia.co.uk/2018/09/17/ibmdiscriminationsuit917.p...
On the surface, allowing recent hires to be exempt from performance-based layoff programs isn't particularly unethical, as they may still be ramping up. It certainly seems like there's substance here, though, beyond just "think like a millennial" or "give recent hires a chance" rhetoric. Will be interesting to follow. It's essential to our entire industry that lawsuits like this draw lines in the sand - we're all in danger as we age if big tech can get away with age discrimination.