Toga, as pilots age, the rate of medical terminations increases significantly. Each Captain who retires or leaves medically generates a significant number of training courses behind them. One A380/B747 Captain retirement could generate 5+ training course behind them. The consequence of this that as both the rate of growth and retirements increase, there is a disproportinate backlog of training. You could potentially have 5~10% of pilots in training at any one time.
The peculiarities of this seniority system, and the implications & consequences appear to have escaped senior management, and the delay in training & recruitment back in 2015 has put them significantly on the back of the drag curve. The training system then became clogged and further exacerbated the issue and increased significantly time off line in the training system (6 to 9 months to do a type course), a training death spiral