Plateauing on pull-ups and dips after consistent RR for 3 months - need advice

I've been consistently following the Recommended Routine for the past three months, training three times a week on Monday, Wednesday, and Friday. My focus has been on building strength in pull-ups and dips, but I've hit a wall. Initially, I couldn't do any pull-ups, and now after using resistance bands for assistance, I'm managing sets of 5 with a medium band, but switching to a lighter one feels impossible. For dips, I'm at 3x8 on parallel bars, but no increase in reps lately. My warm-up includes 5 minutes of jumping rope and dynamic stretches like cat-cow and shoulder rolls. Nutrition-wise, I'm tracking macros aiming for 1.6g protein per kg bodyweight, around 2800 calories total. Sleep is solid at 8 hours, but recovery might be an issue because of work stress. I also do some core work like planks and hanging leg raises. Has anyone experienced this kind of plateau? What modifications or additional exercises helped you progress? I'm 32 years old, male, 75kg, and former office job with poor posture. Considering if I should deload or change the routine slightly. Also interested in incorporating more mobility work for shoulders.