You can try resetting your network settings and see if it improves things. Goto settings and search for reset and from there choose Reset Network Settings. After reset restart your device and see. Please note your data will remain unaffected but your saved wifi passwords and paired Bluetooth device history will be lost.
You can also try changing your sim. And if it still doesnt work then I guess wait for a software update from Samsung. I just checked and received an update today on my S20FE 5G and after update I am still getting 4G+.
