In Exploratory, you can create a survival curve using the Kaplan-Meier method. Typically, survival curves should start at a survival rate of 100%, but sometimes the curve starts at a value lower than 100%.
This issue indicates that there are observations in the data where the start and end times are the same (i.e., the event occurred at the starting time).
There is no problem with plotting such a survival curve; however, if you want the survival curve to start at 100%, you can address this by excluding the data where the start and end times are equal.
For more details, please refer to the link below.