Hi A. Tan,
As per your description, based on my test result in Excel version 16.54 (21101001) and I’m able to use Power Query on Mac OS. See my test image below for your reference:
Since, your Office 365 on your Mac OS is up-to-data and still you are unable to see Power Query option from your side.
Please make sure your file system is OK. starting by checking file system using Disk Utility. If there are file system problems, Disk Utility may be able to fix them.
How to repair a Mac disk with Disk Utility - Apple Support
Also, please try to operate a safe boot for Mac then the outcome. To operate the safe mode is to determine whether background programs are interfering with Office for Mac.
Disclaimer*: Microsoft provides no assurances and/or warranties, implied or otherwise, and is not responsible for the information you receive from the third-party linked sites or any support related to technology.*
May I know does issue happened to specific Excel file? if issue with all Excel files even new created Excel document on your Mac OS, then I suspect components were corrupted somehow. You can go to the Applications folder In Finder and drag Microsoft Excel.app to the trash. Then Restart your Mac Download this installer the Install package and use it to reinstall Microsoft Excel (the latest version 16.54). Then, restart your Mac and test.
If above suggestion does not work for you, please feel free to confirm your MacOS version.
I appreciate your understanding and stay safe!!
Best Regards
Waqas Muhammad