Learn Farsi: به گفته‌ی طراحان، ترندهای پوشاک هر سال تغییر می‌کنند. - According to the designers, apparel trends change every year.

Gofte literally means a saying or statement, derived from the verb goftan (to say). By adding be in front, you get "by the statement". The -ye is simply the Ezafe linking this noun to the source of the statement, tarrahan (the designers). This structure acts as a prepositional phrase meaning "according to" or "in the words of".

Why is the plural of designer formed as tarrahan instead of tarrah-ha?

While -ha is the standard plural suffix for almost anything in everyday spoken Farsi, the suffix -an is frequently used in written and formal Farsi specifically for people and animate beings. Because tarrah refers to a person, tarrahan is a very natural choice in this slightly formal, reporting context.

Why does the verb taghyir mikonnand take a plural ending when the subject, trend-ha (trends), is inanimate?

You likely remember that inanimate plural subjects in Farsi usually take a singular verb. However, in modern formal writing and journalism, it is becoming common to use plural verbs for inanimate subjects, especially for concepts like trends that actively "do" things. Using the singular taghyir mikonad would also be completely grammatically correct here.

Is trend just the English word, and does it follow normal Farsi grammar rules?

Yes, it is an English loanword that is now very common in Farsi fashion, business, and social media contexts. It behaves exactly like a native Farsi noun: in , it seamlessly takes the standard plural suffix followed by the Ezafe to link it to the next noun.