A data breach on a site exposed your password

I have added authentication to my website and it shows a message as shown in the picture when I login or signup. And also I have an option called "Add Comment", which opens only if the user is logged in or else it redirects to the login page. But here when I login and click on the "Add Comment" button it still redirects to the login pageant it doesn't show me the Add Comment page.

Authentication routes:

app.get("/register", function(req, res){
    res.render("register");
})

app.post("/register", function(req, res){
    User.register(new User({username: req.body.username}), req.body.password, function(err, user){
        if(err){
            console.log(err);
            return res.render("register");
        }
        else{
            passport.authenticate("local")(req, res, function(){
                res.redirect("/campgrounds");
            })
        }
    })
})

app.get("/login", function(req, res){
    res.render("login");
})

app.post("/login", passport.authenticate("local", {
    successRedirect: "/campgrounds",
    failureRedirect: "/login"
}), function(req, res){
})

app.get("/logout", function(req, res){
    req.logout();
    res.redirect("/")
})

function isLoggedIn(req, res, next){
    if(req.isAuthenticated()){
        return next();
    }
    res.redirect("/login");
}

Comment Route:

app.get("/campgrounds/:id/comments/new", isLoggedIn, function(req, res){
    Campground.findById(req.params.id, function(err, campground){
        if(err){
            console.log(err);
        }
        else{
            res.render("comments/new", {campground: campground});
        }
    })
})

app.post("/campgrounds/:id/comments", isLoggedIn, function(req, res){
    Campground.findById(req.params.id, function(err, campground){
        if(err){
            console.log(err);
            res.redirect("/campgrounds");
        }
        else{
            Comment.create(req.body.comment, function(err, comment){
                if(err){
                    console.log(err);
                }
                else{
                    campground.comments.push(comment);
                    campground.save();
                    res.redirect("/campgrounds/" + campground._id);
                }
            })
        }
    })
})