PSG and Bayern Munich are both leading their domestic leagues. PSG is at the top of Ligue 1, where they are yet to be beaten, and Bayern Munich is leading in Bundesliga. But what is noticeable is that none of them has used their domestic success in demonstrating dominance in Champions League in this season. But then, it is considered to be a tougher competition. Because the level of pressure and the quality of opponents is higher. Therefore, superior performance in the domestic league does not always guarantee success in European competition.
Neither of both teams have been able to demonstrate their domestic dominance in the champions League because practically they are tow different leagues with varrying form of competitiveness at this point, if I am to even examine them and their strength I wouldn't be making much reference to their domestic performance knowing how well that is very different from the champion's league and even within them the level of prioritization they attach to each of these leagues at the levels they are at. So you are very correct to say that superiority in the domestic league doesn't equate same performance in the champions League.
It is clear that both teams failed to implement strategies and adapt when facing the Champions League. The pressure given in the Champions League is very different from the domestic league, so the results obtained by both teams in the domestic league are not directly proportional when playing in the Champions League.
PSG and Bayern Munich are both leading their domestic leagues. Simply because in terms of talent and player resources, they are always far superior to the domestic league teams.
As for the Champions League, the quality of the teams here is even much higher than theirs. I'm not just talking about the financial aspect but also the smart management of the team's leadership. For example, PSG has the finances but they cannot recruit a truly qualified coach. If compared to Real Madrid, the team always has a talented coach. If PSG had recruited coach Zidane, the story in the Champions League would have been different.
In short, PSG and Bayern Munich still lack the necessary elements to become stronger in this arena.
You are right, the strategy owned by the coach may be the main cause so that both teams, PSG and Bayern Munich, were unable to perform well in the Champions League. But if you take Real Madrid as an example, because this season it seems that Real Madrid is quite struggling in the Champions League, even though Madrid has an experienced coach, namely Ancelloti, but this season Real Madrid has performed less than satisfactory, in the domestic league even though it is in second place in the standings, but Real Madrid's points obtained are far behind Barcelona, as well as the position in the UCL which is not far from Bayern Munich. FC Barcelona is the best example that we can see this season, because besides their success in the domestic league, Barcelona also performed quite well in the UCL, under the guidance of Hansi Flick, Barcelona was able to adapt and perform well in the domestic league and the Champions League.