Battery charging is an ongoing field. There isn't conclusive evidence that fast charging itself is bad. However, fast charging have a measurable impact on battery life in the field
Other variables include discharge rate or temperature also have an effect on battery life too. Like any engineering problem, fast charging is a trade off. The loss of battery life may not be pronounced as the normal 2-year life span usage rate.
Please note, fast charging is not part of the USB standard. Qualcomm, Huawei, Oppo and Apple create their own implementations.
Even worse, lots of cables break the USB C power spec.
Benson Leung regularly validates cables ever since a third party cable kill a chrome pixel.
I am not sure what will happen if you mix up different chargers.