Peter I'm still using my A70 plenty including as I type this, but I'd be curious to know if the change you observed concided with any software patches. I was on May then October and the rendering did change slightly which I think was subtly better before. November patch can't be rolled back from which isn't a big deal since I wanted Android 10 to play with in a few months.
Oh as a side note, I hope you did the setup with a sim card. Samsungs erase themselves the first time a sim card is inserted into a new device.
The Huawei thing is interesting. It uses a Kirin CPU with a Mali GPU. A70 devices use a snapdragon-adreno combo. I did see a P30Pro at a kiosk and I didn't touch it more than a few seconds since I didn't care for it, but I'll look at it again next time. Huawei is politically problematic anyway because of the company's connections to an authoritarian state.