Personas have a bad reputation. I think because they are an often misunderstood method. When used correctly they can be very useful when making product decisions.
The main goal of a persona is to represent a (target) user group for your product. So the only information that should be in the persona is data relevant to a specific product. You can’t reuse personas from another project.
When writing a persona, it’s very important to already have real data about existing users or target users. Examples of useful information to include are: what’s the context in which they use this product, what are they trying to do, what do they expect to achieve with it, and what are they worried about when using it.
Often times, personas are riddled with irrelevant information like “married with 3 children and 1 grandchild”. Is the product meant to be used by people with children? Does having children influence how people use the product? If the answer is no, then why does it matter if they have kids?
As always, Personas are a tool, if they are useful for you use them, if not find some other method that helps you create better products.