SUMMARY
When setting the Power Profile to "Power Save", the Power Management widget in a panel will display the "Power Save" icon (default is a leaf icon) but in doing so the Battery Percentage is not displayed. Changing the Power Profile back to any other setting will display the Battery Percentage again.

I believe in Plasma 6.0.5, the Battery Percentage was still shown, as I just noticed this after upgrading to Plasma 6.1.0 (although I only used Plasma 6.0.5 on this device for a few days before upgrading).

STEPS TO REPRODUCE
1. Add a "Power Management" widget to a Panel
2. Enable the Battery Percentage display option
3. Change CPU Power Profile to "Power Save"
4. Battery Percentage is hidden (but the option is still enabled if you right click on the widget)
5. Turn the Power Profile back up to another value
6. The percentage will display again, it is only missing when the power profile is "Power Save"

OBSERVED RESULT
The Power Management widget will not display the Battery Percentage if the Power Profile is set to "Power Save".

EXPECTED RESULT
The Power Management widget should display the Battery Percentage.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.9.5 Linux Zen
KDE Plasma Version: 6.1.0
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.1

ADDITIONAL INFORMATION
I have only tested the Wayland Session, I did not test X11.