I have noticed that all the Gujarati script fonts available in Google Fonts display રુ (ર + ુ) (Gujarati ra + u-vowel-matra) as a ligature where the u-matra is connected on the side (similar to Devanagari रु). However, the only reference that I have found for such writing style is from a 1949 Gujarati lexicon Saarth Jodanikosh. AFAIK modern Gujarati publications use a normal u-matra below ra ર‌ુ.

રુ in different fonts:

રુ in the word ગુરુ in Saarth Jodanikosh (1949)

રુ in the word ગુરુત્વાકર્ષણ in a 9th Standard Science textbook published by Gujarat State Board (2014)