Thank you so much for your reply.
In the "source span" section on the page recommended it is written that:
"The source fields should be visualized to make sure they have decayed sufficiently at the edges of the source span (at an amplitude of10^3 to 10^4)."
I have understood from this line that if the fields are decayed such that we see only an an amplitude of10^3 to 10^4 then simulation settings should be fine. As from the fig.2 that I have shared above the scale is showing the highest red color field has the power of 0.000569. So, do you think this is already in the range as discussed in the shared article or the results from these monitors are not to be taken care off?
P.s.: I always visualize my mode field of source to see if perfect mode is present inside.

With Kind Regards
Ismail Sarwar