I expected Barcelona to win against Rayo Vallecano. I never expected a strong team like Barcelona to perform so badly as a football fan. They could have definitely lost this match if Lamine Yamal had not scored the penalty. The credibility of the referee's decision to award the penalty is also questioned. If Barcelona continues to perform so badly, it could lead to unexpected results for them in the next matches. I think Barcelona may not have expected the home team to play so well, which is why experienced analysts always say that no team should be underestimated. If VAR technology had worked properly in this match, the penalty decision inside the box would have been overturned.
Barcelona's penalty goal against Rayo Vallecano is still a subject of debate. How is it possible that when the players reviewed the penalty, the referee told them that their Video Assistant Referee (VAR) was not working properly, but the Video Assistant Referee was activated again shortly after the penalty was scored?
First, if there was indeed a technical problem, there is still no end to criticism about this issue because La Liga is undoubtedly a big league and if the normal video assistant does not work properly in important matches of this La Liga, it does not look good.
Second, what did the staff in charge of the Video Assistant Referee do after the penalty was scored that the Video Assistant Referee was activated immediately.
Anyway, Barcelona scored a controversial penalty that is why they did not lose against Rayo Vallecano. If this goal had not happened, they would have lost this match.
You are right that Barcelona would have lost if they had not get this controversial penalty. Lamine Yamal was illegally obstructed by Vallecano players but it was not that serious. In the match between Real Madrid and Mallorca Real Madrid deserved at least four to five more goals but due to the perfect technology of VAR several goals decision was not in their favor. Almost every tournament sees some biased matches which are a disgrace to the game of football as a whole and disappoint the fans.
There is actually no technical problem here I think it is a deliberate mistake because there were enough video cameras around the field and the referee should have watched those videos and made a decision. The result of the match can change like this for various reasons and we call all these mistakes luck when a team loses and wins.