After the break Manchester City is having form issue just because of this now they are losing points in Premier League, but Barcelona is surely having different way like they play in yesterday game against Real Madrid things looking amazing, and we can expect good fight for the next round between these two clubs with most chances both are having equal chance for qualifying into next round because now things looking positive and they both have enough quality and match winners.
First of all, we know about FIFA virus and its impact on clubs that have too many international players. Second many players of Manchester City had very bad World Cup 2022 and they returned to club with bad psychology. Their performance for Manchester City is affected by being tired after World Cup 2022 physically but their psychology was impacted negatively too.
Player who did not participate in World Cup 2022 like Haaland can not return to his best performance yet. Haaland lost his sensitive touches and shots for Manchester City. His injury and recovery time are likely affected him too and he will need a little more time to be ready.
Now how they respond on match day this could be completely different story with win against Manchester City their confidence level is high, and they can beat any team because this is the biggest win under Ten Hag era for them, and they are completely different team with this all.
Time is no longer supports Manchester City even the season is long enough. However the excellent form of Arsenal in this season can turn the season to a nightmare for Manchester City. Bought Haaland who broke many Premier League scorer records but lose the trophy to Arsenal. It's an acceptable ending for Manchester City and Pep Guardiola and they will surely try to avoid it.
I agree with you that the clubs that have too many international active players suffer a lot after big international events like the FIFA World Cup this time around. As you said most of Manchester City's players are from teams like England, Belgium, and Spain and all of these international teams had a really bad World Cup.
Consequently, players are not in form and are in a bad mood and they have lost their team chemistry they had with the Manchester City players.
Pep Guardiola has to fix this as soon as possible because if Manchester city loses a few more matches they might lose the EPL trophy all together