Not a screen protector
Screen protectors can be extremely annoying and a struggle to put on your phone, but they save it from getting cracked when it is inevitably dropped later on. This person realized that their mom had chosen to use the throwaway film on her phone as a (very bubbly) screen protector.
Let’s hope this person’s mom didn’t damage her phone screen too much before her son let her know that the throwaway film actually offers zero protection to her phone whatsoever. Honestly, though, how did she even see her phone screen clearly before her son pointed out her error?