Apple is currently testing iOS 26.4 for enthusiasts and developers. The one for enthusiasts (public beta) is iOS 26.4 Public Beta 1, and the one for developers is iOS 26.4 Developer Beta 2. However, these beta versions caused abnormalities in the charging function. No matter what charger the user used, slow charging would be displayed. That is, slow charging was displayed on the lock screen and slow charging was also displayed in yellow font in the battery options. Many users thought it was a charger problem.
Blue Dot.com is using iOS 26.4 Public Beta 1. After the update, we discovered the slow charging problem and thought it was a charger problem. However, we then replaced the chargers with Cooltech, Anker Innovations and Nubia. Even if we replaced the data cable, it still showed slow charging.
Later, I saw the discussion in the Reddit community and realized that this was a system problem:
After connecting to the charger, fast charging will be displayed for 1~5 seconds, but then it will switch to slow charging warning.
The charging power is limited to 5~10 watts, which is much lower than the normal 20~27 watts (that is, the actual charging speed is slow charging)
Chargers of different brands/powers all show slow charging, even Apple’s own 20W charger
A small number of users also encountered overheating protection reminders, but in fact the phone was cold and not hot to the touch.
Fixed in iOS 26.4 Beta 2:
If you are using iOS 26.4 Beta 1, you should update as soon as possible, because this is not a display problem but really causes the phone to charge slowly. Sometimes the phone is still losing power even when watching videos and connected to the charger. It takes a long time to charge from 20% to 80% with 10 watts of power. Normally, it can be charged to 80% in about half an hour.
However, the public beta version has not yet released the Beta 2 version, so users need to go to the update and switch the channel to the developer preview version, so that the problem can be solved after installing the Beta 2 version. For this problem, it is not appropriate to reinstall the official version of iOS 26.3, so a simple upgrade is the easiest way.