Hi Anastasiya Bakteeva,
Thank you for reaching Microsoft Community. We understand that you are having issues with the display and battery life of your Surface Pro 9 and apologies for the inconvenience this has caused you.
May I know which Surface Pro 9 configuration do you have?
Regarding with the display concern, does it happen when you are switching from one application to another, or when the lighting around you changes, or just randomly? The Surface has the adaptive brightness and contrast feature in which it adjusts the screen brightness and contrast based on the content displayed. Kindly try checking this page and try the steps provided to disable the feature then see if the issue with the display persists: Adaptive brightness and contrast on Surface devices - Microsoft Support. Also, if possible, please provide us with a video of the screen of the device where we could see the issue that you are having.
For the battery concern, yes, the Surface Pro 9 was advertised with up to 15.5 hours of battery life based on typical Surface device usage. Testing conducted by Microsoft in August 2022 using preproduction software and preproduction Intel®12th Gen Core™ i5, 256GB, 8GB RAM device. Testing consisted of full battery discharge with a mixture of active use and modern standby. The active use portion consists of (1) a web browsing test accessing eight popular websites over multiple open tabs, (2) a productivity test utilizing Microsoft Word, PowerPoint, Excel, OneNote and Outlook, and (3) a portion of time with the device in use with idle applications. All settings were default except screen brightness was set to 150 nits with Auto-Brightness and Adaptive Color disabled. Wi-Fi was connected to a network. Tested with Windows Version 11.0.22621 (21H2). Battery life varies significantly with settings, usage and other factors. See this page for more details: Surface battery testing and estimated performance - Microsoft Support
Kindly tr also to go to Windows Settings > System > Power & Battery. Select View detailed info. Under Battery usage per app, check to see which app are affecting the battery life of the device. There are several sort options including "background" to help identify. Validate if there are any installed applications that may be using a lot of power.
Furthermore, please check for the Surface drivers' health through the app then run the Surface Diagnostic Toolkit to run some system checks and repairs and make sure also that all updates are installed in Windows Settings > Windows Updates including Optional updates then see if the behavior improves. See this page for reference: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
For the message that shows on the device that it is dated back to 2019, kindly provide us also with a picture of this for us to check. You may just upload the video and photo requested through OneDrive then just provide us here with the Shared link. See: Share files with OneDrive - Microsoft Support
Kind regards,
Marrion