Diabetic and use Libre app? Swapped from Xiaomi and to A53 and suffered weeks of barely working phone. Let me know when the techies have sorted it; see message to Samsung below:
A53 issue with FreeStyle Libre Link app - please be aware. I sent my new phone back to Samsung to be checked as it was connecting and disconnecting continuously, particularly on WiFi. Basically unusable for weeks, but the phone was checked and fine. I changed the SIM. No help. Finally removed apps and it was this important health app for diabetes. Really important to the customers who use it, to the point where if I could go back, I would have avoided Samsung. In the end I am ditching the app, not the A53 but please try to sort this out. It is a major health issue for tens of thousands of people who have diabetes and buy Samsung phones.
I recommend you check out the reviews in Play Store, it's the app which is the issue. You could contact the developers for assistance, you will find their contact info on Play Store.