Unlike the flagship Galaxy S20 range of phones which have Corning's Gorilla Glass 6 both front and back, the Galaxy S20 FE only sports Gorilla Glass 3 on the front and a plastic back.
Probably not since there is no wrongdoing or misrepresentation on their part.
Corning's Gorilla Glass 3 was first used on the 7 year old Galaxy S4 models and there have been no issues with its level of protection offered. I would always recommend a tempered glass screen protector on a new phone, as well as a case, for added protection.
Your previous phone, Galaxy S9, came with Corning's Gorilla Glass 5 both front and back.
as said by ironass the gorilla glass version mounted on the s20fe is a pretty old spec compared to the s9 one.
My advice would be to mount a domeglass on it