I leave this comment if someone suffers from this, exact same problem. I had this trouble too, and I could fix it by matching the font type. Match the font in the ppt file and Illustrator. For example, Arial(title), Arial(text), and Arial (in the list of fonts) make different results in Illustrator. Change the font 'Arial' with nothing. If you cannot make it, copy the objects you want to paste > paste in a new ppt file > change font > copy and paste in Illustrator.
I hope this comment helpful.
I leave this comment if someone suffers from this, exact same problem. I had this trouble too, and I could fix it by matching the font type. Match the font in the ppt file and Illustrator. For example, Arial(title), Arial(text), and Arial (in the list of fonts) make different results in Illustrator. Change the font 'Arial' with nothing. If you cannot make it, copy the objects you want to paste > paste in a new ppt file > change font > copy and paste in Illustrator.
I hope this comment helpful.