Laying off then re-hiring at reduced pay and benefits, a common practice not confined to the tech industry or FAANG. Also a way to get rid of troublesome and unproductive people under the guise of a mass layoff. Labor unions exist in part to prevent that practice. I'll let you work out why companies might prefer hiring people with less experience, or discriminate against older and more experienced people -- a practic…
As someone who started in the industry in the mid-1980s, this practice was very well known back then, as I'm sure it was very well known before then.
At the start of my career in my mid-20s, we all talked about it all the time - that by 35-40, you are either in management or whatever else. But not a coder, for the most part, except for exceptions.