Hi,
Your son is in the midst of Rahu Maha-Dasha, who is placed alongside Ascendent or Udaya Lagna in the Zodiac sign of Sagittarius or Dhanur Rashi and has below par Vimsopaka Bala in Dasha-Varga. So, it is quite normal for the native to be a little lazy, care-less, distracted, seemingly uninterested in studies, taking things lightly etc. Thankfully, Rahu seems to be in a calm mood.
Incidentally, Rahu is in Sukshma Parivarthana with Venus/Shukra at Nakshatra level making him a bit more distracted with expressed interest in female friends and worldly pleasures.
Please consider propitiating Rahu to help him overcome the challenges in the current time-period.
Take care…