Barcelona often experiences difficult things like this, and what's worse is that last season, Barcelona had to sell some of its assets to get money to be able to pay salaries to its players who had very high salaries. I'm sure Barcelona will still survive and try to attack when there is the right time, because the reduction in Barcelona's core players has reduced their playing performance.
Last season they didn't get much income to increase finances and this season is an opportunity Barcelona has to make more money by winning more matches, UCL is one of the leagues that can provide bigger amounts of money.
When this season Barcelona is able to achieve more UCL wins and can also win the La Liga title then they will not be like last season, even next season when the transfer window opens before the season starts there will be more budget to bring in several players.
The money spent on football team actually depends on how the team develops in each league, even winning the championship can bring in more money.