Try:

=MEDIAN(FILTER($I$2:$I$20,$D$2:$D$20=L2))

AliGW on MS365 Beta Channel (Windows 11) 64 bit

L
M
N
1
Month Mean LOS Median LOS
2
Aug-23
1.25
1
3
Sep-23
1
1
4
Oct-23
2.71428571
2
5
Nov-23
1.5
1.5
Sheet: Sheet1