I personally think that the S20 series does not live up to it's price. It's insane that a phone that costs so much has so many issues. First the camera sucks! I have all of the updates I should have and the camera still isn't clear....everything is fuzzy. They phone is made so poorly that you have to armor it, if not one drop and it's going to be either bye bye to the screen or camera. The phone glitches all the time google assistant turns on when it wants. The list goes on. I truly think we should get a discounted price, be able to get the S21, or a discounted price as this phone definitely didn't live up to it's expectations. My son's iPhone works better and so does the camera and I have never went to iPhone but I'm considering because they seem to deliver.
I'm not sure about the S20, but you have described my A20 & it was considerably cheaper than your S series but it was still like $250 & I started having trouble from it within the first few weeks. Not at all satisfied with this one. I need to get my Note9 screen fixed then I'll be happy.
I'm not familiar with the A20 series but I agree this phone is very irritating at times and sometimes doesn't preform the way it should. When we went to upgrade they made it seem like it was the best phone ever made......and when we got the phone it was nothing like that at all. Yes it packs some awesome features but one thing I am upset with truly is the camera. It take such blurry photos and it's hard to get it to zoom in enough time to take a pic. I think by far this was the worst model line. I had an s8 before this ans it was way better.
What really angers me about the camera is how they removed the ability to change the resolution for both the front and rear cameras for photos. You can still change the resolution for videos but the option was removed for photos. For a phone this expensive that used the camera as a selling point to remove the ability to change the resolution is an insult.
You are still better off with S20s when it comes to 8k camera than S21s. Half a minute of 8k recording takes close to 250 mb space and with no option for a micro SD card, you won't go far with 128 gb storage. Sometime one wonders what Samsung was thinking. They have been pushing 8k TVs, and as yet falter miserably when it comes 8K camera phones.