It is common practice to lose one to five eyelashes per day on average. Although this may seem like a lot, it’s important to remember that we have 70-80 lashes on our lower eyelids and 90-150 lashes on our upper eyelids. Losing a few lashes each day is normal and not something to be concerned about. Many people suffer from lash loss, which is a common occurrence. Although it is normal to lose a few eyelashes each day, excessive eyelash loss can be troubling.
Source: https://justcareprost.com/how-many-eyelashes-are-usually-lost-in-a-day/