ML algo suggests alpha=2 but alpha=3 gives better accuracy

[stuck rapids]

trying to get best accuracy with hyperparameter tuning, here are the results so far

alpha 2 is suggested and accuracy is 98.65%

alpha 3 was not suggested but accuracy is better - 98.83%

im confused because I thought this method was supposed to give us the best accuracy parameter? i just randomly put alpha 3 and got a better result