We had heavy rainfall for several days in a row, so it did not appear to be an active leak. It may have been repaired in the past. Nonethelast, water leakage next to an electrical panel is a concern. Fortunately, our buyers were with use for the inspection and the issue was pointed to them. Our recommendation in the report was to ask the seller about it. In this case, we considered the stain to be a big deal because water and electricity do not mix.
It is important to know if the leak was discovered and repaired in the past, then all is well. Or, if the seller was not aware of it, then immediate action is required to fix the unsafe condition.