PHP comparing number get error it just simple comparasion

i write code like this:

$a = 1.84;
$b = 1.84;

if($a==$b) echo "na equal bn";
else if($a<$b) echo "na less than bn";
else if($a>$b) echo "na greater than bn";

i’m so confused why the result like this:

enter image description here

while i compile in other php like online php, the result is correct “a equal b”. is there any problem with my php? PHP 7.4.33