A 58-year-old man with hypertension and type 2 diabetes mellitus undergoes elective laparoscopic cholecystectomy under general anaesthesia. After induction with propofol (2 mg/kg) and intubation with succinylcholine, his blood pressure drops to 85/50 mmHg and SpO₂ falls to 88% on FiO₂ 1.0. Breath sounds are present bilaterally. Heart rate is 110 bpm. The anesthesiologist notes the capnograph shows a normal waveform. What is the most likely cause of hypotension in this patient?