Laravel Return Redirect Back Variables Not Working Sometimes

i have a weired problem 1 : i submit form in a.blade.php and send params to controller x in my controller x i di some action i now i want return user to a.blade.php page with some variables such as result by redirect back() :

return back()->with(['var1' => '2']);

in my a.blade.php i get params like as :

BUT Problem is : sometimes this var1 working and show result by sometimes NOT WOrking ....

via Chebli Mohamed