Index of not working for a string value

[anfield]

I have an issue finding a string in an array. Have confirmed via logging that the values in the array are strings, and the variable is of type string. Can someone help me with what I am missing?

function check_usage(all_users){

	var gdt = new GlideDateTime();
	gdt.addMonths(-2);
	var months_ago_format = gdt.getDate().getByFormat("yyyy-MM");
	var months_ago_str = JSON.stringify(months_ago_format);

	gs.log('Demand log: check usage: months ago: str ' + months_ago_str + typeof(months_ago_str));

	var obj_len = Object.keys(all_users).length;

	for (i=0; i< obj_len; i++){

			gs.log('Demand log: check usage: userid: ' + all_users[i].user_id + ' acc dates: ' + all_users[i].accrual_dates);
			
			var TF = all_users[i].accrual_dates.indexOf(months_ago_str);
			gs.log('Demand log: check usage: TF:' + TF);

	}

When I log the variable months_ago_str, the log looks like this

Demand log: check usage: months ago: str "2023-05"string

If I put that directly into the indexof brackets I can see that it is working, the log shows different index values for where the string is found. When I try and use the variable above though, it always produces -1.

The data itself looks like this. I am searching that array "accrual_dates". I think I am on the right track but something is throwing this off. 

Thanks in advance

Log Object: Demand Log: App Usage: all users3
Array of 10 elements
[0]: Object
user_id: string = user1
accrual_dates: Array of 1 elements
[0]: string = 2023-05
[1]: Object
user_id: string = user2
accrual_dates: Array of 5 elements
[0]: string = 2023-06
[1]: string = 2023-07
[2]: string = 2023-06
[3]: string = 2023-07
[4]: string = 2023-05
[2]: Object
user_id: string = user3
accrual_dates: Array of 1 elements
[0]: string = 2023-07

[Sonam Tiwari]

Useful reference to undertstand the difference :

https://community.codenewbie.org/sophieopera/what-s-the-difference-between-json-and-a-plain-string-4...