I think one of the most common user experience problems is when people are trying to use a website or app and they can't figure out how to do what they want. This might be because the interface is confusing, or the labels are unclear, or there are just too many steps involved. When this happens, people usually give up and go somewhere else.
Another common problem is when people are trying to complete a task on a website or app and they keep getting interrupted by ads or pop-ups or something else that distracts them from what they're trying to do. This can be really frustrating and again, people will often just give up and go somewhere else.
There are a few things that can be done to try to avoid these kinds of problems. First, it's important to have a clear and well-organized interface. Second, labels and instructions should be clear and concise. Third, it should be easy to complete the task without too many steps or distractions. Of course, it's not always possible to avoid all user experience problems, but if these things are kept in mind, it can help to reduce the number of problems that occur.