Here are some things you can check to make sure your PowerPoint presentation is displaying the correct font size for object labels:

1. Check the Design tab and look at the Fonts section to make sure the fonts you've selected are set at the size you want.
2. If your labels are inserted shapes, go to the Format tab and make sure the Size & Properties settings are correct.
3. Check the Size section of the Formatting task pane to make sure the font size is set correctly.
4. Make sure your text boxes are not set to autofit, as this will adjust your font size based on the size of the box.
5. If your slide has a custom background, check to see if the font size is too big for the background.
6. Finally, if you are using any custom font styles, make sure you have the necessary font files installed on your computer.