[deeblering4]

You are overlooking the fact that the word is flagged as offensive. That is the entirety of the issue.

Definition of retarded

1 informal + offensive : very stupid or foolish

2 dated, now offensive : affected by intellectual disability : INTELLECTUALLY DISABLED

[Gigachad]

That still fits. OP is describing the product which they believe to be sub standard and likely want to imply offense to it. There would be a difference between "This product is shit" and "You are shit". Both are sending offense to the target, but one of them is a computer with no feelings.