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I can't speak for other companies but I work at Google and I've met several people over the years who've confided with me that they've been on PIP (either in the past or at the moment when talking to me). While (thankfully) I haven't been on PIP myself (yet!) so I can't speak from personal direct experience, I can confidently say that all the people I know personally that were on PIP have successfully re-focused their career, haven't gotten fired, and are still working at the company years later.
Obviously it might be survivorship bias and I might simply not be meeting those that do not succeed, but at least I can confidently say that being put on PIP itself is not necessarily just an excuse to get you fired.