It was the most curious match of this stage of the Champions League and to be honest, considering how many mistakes the teams made, we can say that it was not a game of the Champions League level, but rather resembled the games in the conference league, because the level of play of the teams was very low.
In fact, all three goals conceded by Girona were the fault of Girona's players and it was especially frustrating to concede goals in the very end, especially considering that they were the winning goals for Feyenord.
Girona have 0 points in 2 games so far, plus Tsigankov is injured, which means there are even fewer options to put in the attack. We can say that Girona have only one normal striker left, it is 37 year old Stuani and in general I think the results of Girona will only worsen in the near future unfortunately.
Girona is on decline, but things are having not bad for this game as lady of luck was not with them and Feyenoord were lucky enough to have won this game overall Girona done job, but they need improvement because in this season until now they are having 10 games with just 2 wins and 5 loses mean things are going from bad to worse for them.
In start of this season, things were not favourable, but they have good start but suddenly now injuries and lack of quality is going to have huge impact on their campaign for this season mostly peoples were expecting situation like this because they are having idea average clubs like Girona not able to keep things on good level for long time just one season were enough now they are going back to their normal position as struggle for the relegation zone and keep things middle and lower half of the league table.
I agree with you that last season was more of an exception for Girona. Last season was successful for several reasons for Girona and mainly because of well chosen tactics and good scoring players like Tsygankov and Dovbik and the sale of the latter had a big impact on Girona's attacking potential. Now big soccer is primarily a matter of big money, because you can accidentally play great one season, but without big spending on transfers, there is no chance for a team without big money to become leaders in their championship. There are exceptions when a team finds an incredibly talented coach who makes real stars out of ordinary average players, like Unai Emery with Aston Villa, Villereal and Sevilla, but this is more of an exception.
So without any big transfers and after selling their main striker, Girona are legitimately failing this season.