Yup, not sure what it's at now, but with low mempools that limit was around 20k sats. If you make a number of payments under that value, it's all trust. Then when you finally hit a big enough payment or go over 20k, you pay the fee for all the previous ones. You could use their recovery tool to get those funds back on chain before it gets to that point. There's several areas where Muun literally lies about your balance in the app too.