Based on what you provided, I believe there are two separate issues here: the blinking amber MagSafe indicator and the change in indicator color when your battery reaches its 80% charging limit.
1. Blinking amber MagSafe indicator
According to Apple, a MagSafe 3 indicator that repeatedly flashes amber may indicate a charging issue. Since you've already tested the cable and power adapter separately, I suggest the following:
- Disconnect the MagSafe cable from your MacBook Pro and the 96W power adapter.
- Unplug the power adapter from the electrical outlet.
- Inspect the MagSafe connector and your MacBook Pro's charging port for debris, particularly small metallic particles attracted by the magnets.
- Clean the connector and port carefully with a dry, lint-free cloth.
- Restart your MacBook Pro, reconnect the power adapter, and test charging again.
If the problem persists, try charging through one of your MacBook Pro's USB-C ports using the 96W adapter and a suitable USB-C charging cable.
If USB-C charging works consistently but MagSafe continues to blink, the problem may involve the MagSafe cable, charging port, or their communication rather than the power adapter itself.
Apple provides additional troubleshooting instructions here: If your MagSafe cable or power adapter isn't working
2. Green MagSafe indicator at the 80% charging limit
Yes, this is expected behavior with the newer macOS charging-limit implementation.
When your MacBook Pro reaches its configured 80% charging limit, macOS considers the battery charged to its selected limit. The MagSafe indicator can therefore turn green even though the battery hasn't reached 100%.
This behavior was also reported beginning with macOS Tahoe 26.5, so it isn't necessarily a new change introduced by macOS 27. You can verify this by selecting the battery icon in the menu bar. It should indicate that the battery has reached its configured charging limit.
Apple explains the feature here: About Optimized Battery Charging and Charge Limit on Mac
The green indicator at 80% isn't a cause for concern. However, the repeated amber flashing and the need to reseat the MagSafe connector aren't normal and warrant further investigation if the troubleshooting steps don't resolve them.
