Why are there so few new signings in La Liga?

The summer is usually a period of trials and new faces. The former starts to happen with the first pre-season games, but the latter is taking its time to kick off in a summer without rest.
La Liga has regained the potential to attract stars in recent years with the presence of Jude Bellingham and Kylian Mbappe, as well as the emergence of Lamine Yamal, but has lost the financial capacity to sign other players under contract.
This, in turn, has led to a stagnation in the clubs' finances that prevents a clear movement of top players. In this summer full of competitions - first the European Championship, now the Olympic Games and when they end the season has already begun - the Spanish market is seeing little activity, especially at the big clubs.
So far, with just over a month to go until the market closes, Real Madrid are the only one of the big three Spanish football teams to have signed big names this summer as they have signed both Kylian Mbappe and Endrick.
While Madrid have signed two players, Barcelona have signed no one so far. The Catalan side are insisting on the arrival of Nico Williams to sign the best flanks in the league, but at the moment it is not possible due to their finances.
Their plan B is Dani Olmo, for whom they have already made an offer that has been rejected by RB Leipzig. The third of the big names in Spanish football is Atletico Madrid, who have only signed Robin Le Normand to reinforce their defence.