If I have an equity stake in the company like shares that I have or will exercise, and I think there is some insight I can provide that will help the company improve which will make my shares worth more, then sure, I'll be honest.

Interestingly enough at my last job, I had two separate bosses reach out to me and ask, "can you please say this bad thing about so and so, the company really needs to hear it." I'm not sure why an outgoing employee would be listened to more than my bosses, but whatever.