There are nine quavers (or eighth notes) in the bar. The fact that the right hand plays the second quaver of the first beat is probably confusing you.
Let's number them for you:
LH bass D♭ (A♭ is held from the previous bar)
LH F/A♭ (&hold)
RH F/A♭ (&hold)
RH D♭/F (&hold)
In Schubert's music, "D" stands for "Deutsch Number." Otto Erich Deutsch prepared a catalog of Schubert's compositions and thus got his name on the catalog.
Ludwig von Köchel did the same for Mozart and thus Mozart gets "K" numbers.
It's based on Ary Barroso's 1939 song Brazil - Aquarela do Brasil. Although it doesn't use the melody, the backing is the same. And it's a samba, or strictly speaking an 'exaltation samba', of which style Barrosa was the chief exponent.
At the time, much effort was being expended on projecting a positive image of Brazil: on creating a new identity. Getúlio ...
To address the probable cause of confusion, notice that the first notes played by the right hand are quavers beamed with the quavers from the left hand. If you mistake them for crotchets whose stem happens to overlap the beam, then it would indeed look like the bar is one quaver too short.
Performing classical music is difficult. Many performers are nervous and anxious and their breathing can become shallow fast and noisy. I doubt that any string player would breathe heavily for effect. As an ex- professional l know that any player can be struck by bouts of heavy breathing, especially in situations where their careers are on the line. Flight ...
The incomplete measure has a duple -- two notes take up the space of three normal eighth notes (quavers).
Now, the first full measure: Each dotted quarter (= "dotted crotchet"?) gives us the equivalent of three eighth notes. Also, the three eighth notes at the beginning of the bar give us three eighth notes. The left hand plays low notes (D♭ and A♭, ...