Hi
mhic25Thank you for your asking. Since my device doesn't appear this issue, please try some stay-at-home troubleshooting tips below
1. Check your notification setting in Messenger, is there any different between yours and your brother's?
Messenger>Notification & sounds>Manage notifications
2. Check your Messenger version, is it the latest version? Which version?
*Mine: 266.0.0.16.117
If the issue remains, please provide:
1. Model Name: Settings>System>About phone
Refer to the link below to check the model name by model no. in the link
https://www.asus.com/support/FAQ/1014441/ 2. Your current firmware version
Setting >System>About Phone>Software information
If you try to update to the latest version, does the issue still remain?