Makes sense. Assuming a constant rate of deaths the more removed from the vaccination the death is the less likely it is to be reported to VAERS.
Even if the rate of heart attacks stays constant, it makes sensed that a person having a heart attack the evening they got the shot is more likely to be reported to VAERS than someone having the same heart attack one week later.
This is a fundamental feature of VAERS and one of several reasons it has limited uses.
If it were 90% of the deaths occurred within 24 hours, would you be concerned about the safety of these vaccines?