Based on my experience at multiple Fintechs, one of the most honest metrics you can analyse is that of contact rate. Understanding not just the overall contact rate of your customers but the reason they are contacting is a really clear way of knowing the least intuitive parts of your platform. It will obviously show you reasons you are already aware of but dig a bit further and you will find many parts of your platform where users are getting stuck and you need to spend time on improving. This is better than simply asking users or your support teams because recency bias will impact their answers and cause you focus potentially on problems that are one off. I have used this many times previously and it has never failed in having a strong correlation with improving Net Promoter Score which many Fintechs obsess over. Often these issues can be simple to fix too. For example, if you have customers that are contacting at a certain part of sign up then something might be confusing in the copy that can be changed in a day.