Agile Leaders Don't Account for the Learning Curve

Only things that bring value to the customer count toward velocity. Can you create estimated user stories for say maintenance tasks. What's one common mistake that agile leaders make? There's actually there's actually a few. Sometimes what I see happening is that agile leaders don't account for the learning curve. So just looking at the realities and thinking about what what the teams need to do to shift towards that new way of working.