It’s not necessarily the sale. Some private equity companies move from “Let’s invest like we’re shooting for the moon” to “Let’s invest like we want to improve margins and flip this on 3-5 years”
It’s not inherently wrong but it is a different model, and sometimes companies suffer as a result.
And some (Broadcom) see a product in decline, but with some amount of stickiness/lock-in. They cut R&D and extract value as it withers away.