failing to print not matched lines from second file

[tester_V]

with open(DIR/'lines_to_look_for.txt', 'r') as file:    lines = set([line.strip().split(',')[3] for line in file]) with open(DIR/'check_for_lines.txt', 'r') as file:    for line in file:        line = line.strip()        if line.split(',')[3] in lines:            print(f'{line} MATCH')        else:            print(f'{line} NO MATCH')

I appreciate you help but,
I Could not make your doc work.
it produces wrong outcome.

03/28/2021,P,16,LINE1 NO MATCH
03/28/2021,P,6,LINE2 MATCH
03/28/2021,P,9,LINE3 NO MATCH
03/28/2021,P,9,LINE4 MATCH
03/28/2021,P,8,LINE5 NO MATCH
03/28/2021,S,95,LINE6 NO MATCH
03/28/2021,S,1,LINE7 NO MATCH
03/28/2021,P,46,LINE8 NO MATCH

or if I switch file-1 and file-2

03/28/2021,P,6,LINE2 MATCH
03/28/2021,P,9,LINE4 MATCH

I need :
03/28/2021,P,16,LINE1
03/28/2021,P,9,LINE3
03/28/2021,P,8,LINE5
03/28/2021,S,95,LINE6
03/28/2021,S,1,LINE7
03/28/2021,P,46,LINE8