iPhone 12 Pro (spring 2021) randomly discharges on Qi pad or the Lightning connector on my clock radio.

I have an iPhone 12 Pro (second line in the Sprint/T-Mobile family plan I bought for my son decades ago, mostly as a bedside alarm and for unlimited data for streaming while traveling) that used to charge just fine plugged into a Lightning cable, or the Lightning connector dock on my clock radio. I bought a Belkin flat Qi pad to charge my watch, AirPods Pro and the phone (I had used the stand for my watch and the earbuds, with the phone on the clock radio) to clear clutter from my nightstand—then after a year sometimes it started discharging when on the iHome clock radio’s Lightning dock). The Qi pad’s power light is on, the watch charges (hanging on the stand, it used to discharge if the slightest bit askew) and the AirPods’ case light is on. The phone usually charges to 100% but sometimes when I wake up it’s down to 64% and even on occasion all the way down to 8% and in low power mode. I have to plug it into a Lightning cable to get it back to 100%, and when I place it back on the pad in just the right place it buzzes and I get the green circle stating “100%.”

My primary mobile phone (with AT&T) is a 12 ProMax, which I keep charged in my downstairs office via a Lightning cable—but I recently bought a lightweight 3-device non-Belkin/non-Mophie Qi stand (angled vertical pad for phone, magnetic disk from which the watch hangs, Lightning connector for the earbuds) that works just fine for when I travel. The Pro has fewer lenses and a flatter back profile than the ProMax, so why do I have more Qi trouble with it than the ProMax? And why did it start randomly discharging when in the clock radio’s Lightning dock? I almost never remove it from the charger except when someone I know texts or calls me on that number (which almost nobody knows), or the rare occasions when I stream while traveling.