I have a GalaxyA20 and woke up this morning to see that my phone did a system update and I HATE!!!!!! it. I am no longer able to swipe down to see what notifications I have got.
Please share the device's model number and the software version it updated to. The Swipe down to see the Quick Panel for notifications should still be there.
It may or may not be an issue from faulty update...
I'm wondering if there's a setting for the swipe down to open Quick Panel that shows notifications, but I don't recall such settings option.
I suggest you submit error report to Samsung Members after reproducing the issue & screenrecording of the issue.