I had an 820 and the display halo was exaggerated.
I purchased an 830 hoping that the halo would be fixed but it has not. I requested a warranty replacement but after a little over a year, the replacement device has also ended up showing the halo. From what I have seen on the forum, the same thing happens on other models (e.g. the 1030.).
I contacted Garmin again (with the original out of warranty but with just over a year with the replacement) and here is the response from Garmin (translated from Spanish):
"Thank you for contacting Garmin Iberia.
We inform you that the situation of your screen is a limitation of the same, given its transflective characteristics the behavior you describe does not meet the requirements to consider it a factory defect and does not prevent the use of the same.
Thank you for your inquiry."
Conclusion: we have purchased a device whose own manufacturer recognizes that it does not have sufficient quality to last 2 years in decent conditions. Take note.
Left: May-2020 (five months after purchase). Right: August-2021. It was sent to Garmin and merited replacement. The replacement follows suit but now received the above response from Garmin.