My answer is this
1. Xiaomi phones are charging more and more slowly, indicating that your battery is at the end of its life.
2. Because all batteries have a life span, batteries that are used for a long time will break down and charge more and more slowly. So I think that Xiaomi mobile phones are charging more and more slowly, which means that your battery life is up and needs to be replaced. After replacing a new battery, the problem becomes less interesting.
This will not, it will only get faster and faster, battery capacity with the number of times the battery capacity will get less and less, so charging will only speed up