Thats not a TEXTobject, thats a MTEXTobject (important difference)
Inside a Mtext you can overwrite some things like the font with "internal mtext formats".
Are you familiar with blocks and object propertie values ByLayer / ByBlock? In parts mtext-content inside mtext is like lines in a block.
You have textstyle with them properties, one of them is the font for example arial.ttf
The mtextOBJECT referenced to a textstyle.
Each character inside the MText has the propertie Font=ByTextstyle* and the character is displayed in arial.ttf
Now you can change this. MTedit, select your mtext, Select some or all characters and set Font to Webdings.
The mtext object referenced to a textstyle with font arial, but the chars displayed in font webdings.
And you can see it: Select your mtext object, look into propertiepalette, row CONTENTS. You can see more than your normal MText value, right?
An other example is the color. The color of each character is "ByMtext"*
If MTextcolor is set to ByLayer, the MText content is displaying in the color of the layer.
If MTextcolor is set to color6, the MText content is displaying in the color of the mtext object(6)
If you overwrite the character color inside the MText-Editor with color4, the characters will display in color4,
not in the color a mtext layer and not in the color of the mtext object.
Now the Font and the Color of these charcters are totally independent of textstyle-font and layer-color or mtext-object color.
Removing internal formats
mtedit, select the character(s), set propertie back to nomal value or right-click/remove formats (oslt)
One cool third part program to remove them: stripmtext.lsp
* These are just my fancy words to explain it, not standard AutoCAD vocabulary!