I'm sure on Camp Nou they'll focus and show their best version. You're surely exaggerating. To me it's classic case of complacency from playing in a weaker league. We're talking about the last year's CL finalist after all. How bad can they be really?
Nope. You could say you are complacent when you are leading and don't care that much. This season, PSG are leading nothing. LOSC is above, Lyon is above. They lost and were totally dominated by Lyon at home.
Finished top of the group in CL with some flukes. Leipzig dominated PSG left and right and lost thanks to a very lucky penalty kick PSG got. Was this complacency too ? PSG had less than 35% possession at home in a very important game for qualification.
Last year CL finalist doesn't mean anything. Real Madrid were 3 time CL champions before they crashed. Tottenham were CL finalist before they got a terrible season and fired their coach.
See for yourself, this team is really really bad. Only Verratti, Navas, Neymar are keeping it floating.