I get why it feels that way, especially when your bet is doing well and the cash-out looks lower than expected.
From what I’ve seen, cash-out is just based on live market pricing, so it constantly adjusts with the odds and how the game is unfolding. Because of that, it can feel “off” at times if your selection is already in a strong position.
On Brokerstorm I’ve noticed the same behaviour as well, it follows the live market movements pretty closely, which is pretty standard across most sportsbooks and exchanges.
In the end, it’s really just an option. If you’re confident in your pick, it often makes sense to just let it run rather than cashing out early.