Paypal Payment issue (error on last or first name when i put sng)

[gig1]

i m integrating the paypal payment for web application i m able to pay but getting the error only when i put last name "sng"
i donot why this is occuing but getting the error .
can any body help me to fix this.
here is the json response i m geting when entering last name "sng"
{
"errors": [
{
"data": [
{
"fields": [
"user.last_name"
],
"code": "INVALID_LAST_NAME"
}
],
"message": "OAS_VALIDATION_ERROR",
"path": [
"approveGuestPaymentWithCreditCard"
],
"checkpoints": [
"onboard_user"
],
"meta": {

}, "contingency": true, "statusCode": 200 }

],
"data": {
"approveGuestPaymentWithCreditCard": null
},
"extensions": {
"tracing": {
"version": 1,
"startTime": "2021-04-05T04:02:35.457Z",
"endTime": "2021-04-05T04:02:38.657Z",
"duration"[Removed. Phone #s not permitted]
"execution": {
"resolvers": [
{
"path": [
"approveGuestPaymentWithCreditCard"
],
"parentType": "Mutation",
"fieldName": "approveGuestPaymentWithCreditCard",
"returnType": "CheckoutSession",
"startOffset": 1736284,
"duration"[Removed. Phone #s not permitted]br />}
]
}
},
"correlationId": "900a85dfa82bb"
}
}