My company has a post-logout survey that generates good response rate.
yuliya alt

Hi Yuliya,

It’s a bit hard to say without knowing the context in which your users may choose to log out in relation to your product (are they ending their usage with it?), but if it’s a regular activity, I don’t see a problem in capturing their interest in becoming part of your panel at that point in time.

Alternatively, perhaps you’d like to suggest a proactive approach, where they can choose to opt in during the sign-up process?