really sad, but i don't ever hear that from any phone samsung had removed it yet. kindly check in settings. i have brought a51 just last Friday and after update i also could not find it in phone though phone supported. so i had downloaded it separately from galaxy store. try it. u will sure find it in galaxy store. generally samsung removed it as blotwere may be so.
Samsung pay with NFC support was even available in my 3 year old Samsung j7 phone. but recently 3-4 months ago they have removed the support of NFC from my j7. now its supporting UPI only hence Samsung is degrading and removing its features after providing it. this is fraud played by Samsung.