iPhone battery drain when using CarPlay after iOS 26 update

Issue:

Since the iOS 26.x update, CarPlay has become almost unusable. My iPhone battery drains faster than wireless MagSafe chargers can charge it. For example, I start my morning drive at 100%, but after about 2 hours the battery is down to 70–80% — even though the phone has been on a MagSafe wireless charger the whole time.

This is very frustrating, because my main use of the phone in the car is CarPlay with Waze and Apple Music.

What I’ve tried:

• Tested in three different family cars with different CarPlay systems and wireless chargers — all worked fine before, but the issue appeared in all cars at the same time right after the iOS 26 update
• Closed all background apps
• Removed the phone from the charger in case of overheating (but the weather is cool, so heat is not the cause)

Device details:

• iPhone 15 Pro Max
• iOS 26.0.1 (23A355)
• Battery Health: Normal, 90% (Cycle Count 322)
• Issue started directly after updating to iOS 26.x
• Still persists after the minor 26.0.1 update

Request:

• Any advice or ideas to fix this?
• How difficult is it to downgrade from iOS 26.x to an earlier version? CarPlay is critical for me, and if the phone can’t hold charge while using it, that’s not acceptable.