Thank you very much friend, I unchecked my country (Spain) and left only Wolrdwide, and now I can use YAY, I have been able to update all the EndeavorOS packages without problem.
It seems that there is some error with the Spanish mirrors. I updated them several weeks ago, but I think Welcome was updated recently, maybe that could be the error (I don’t know, I’m new to Linux).
Thanks friend, I’ll try to install flatpak now!