Previously, such a historical pattern was with the European Championship, there were no exceptions, but in 2008 and 2012 Spain broke the pattern. So I wouldn't rely on history when betting - in fact there is no correlation that would prevent the previous champion from repeating its success. I would even say that the champion (the team cannot accidentally become the champion in the vast majority of cases) has more chances, since it was already the strongest.
Yeah, historical data is a bit unreliable. For example, Italy didn't qualify for this world cup, but the last time that happened was in 1958. Most people would have assumed Italy would qualify and make a bet that shows that.
On the other hand, Brazil has qualified for every single world cup, and they qualified for this one unbeaten. History does have some weight, I would say Brazil is one of the best teams in the world cup.
But then again, from time to time the unexpected might happen. That's partly why football is so entertaining. Even the best team can lose to the worst team because of one mistake. You don't see that in some other sports in which one mistake doesn't matter too much.
Looks like your data is a bit out of date ;-) Check out how Italy performed at the World Cup 2018 and you will be surprised. But by the way, this is also a good example - after all, Italy consistently got into the finals of the World Cup and no one could have imagined that in 18 and 22 years it would collapse. And obviously this had nothing to do with the quality of the game of the Italian national team - in 2020 they became European champions and then in 2021 they took third place in the League of Nations. It turns out that this result was completely illogical and unpredictable, but it happened as many as two times in a row.