What is Chrome OS Diagnostics?
Google has released Chrome OS Diagnostics with the rollout of Chrome OS 90. You can use the Diagnostics app to check for and troubleshoot hardware problems on your Chromebook, like issues with the battery, CPU, or memory.
Note: Diagnostics is only available on Chrome OS devices that have version 90 and up.
For further details, please see Googles support page at https://support.google.com/chromebook/answer/10566784