Using filterByFormula for GET list using id in array

Below is my database table structure

{
“id”: “recudh2aihP7c5Xrl”,
“fields”: {
“amount”: -9000,
“type”: “loans”,
“note”: “loaon ami for march”,
“loanFk”: [
“recazeHVfHg52dTFn”
],
“user”: [
“recbPHNfFnjZOaba5”
],
“Name”: “loan ami”,
“createdDate”: “2020-05-03T07:05:26.000Z”
},
“createdTime”: “2020-05-03T07:05:26.000Z”
}

I want to filter records using GET API using the “loanFk” key.

Can someone help me how to put the filterByFormula as it is to be done on an array?

Is there anyway i can convert the array to string as I dont have multiple links