In China, if you are over 35 and not in a leadership role, you are at high risks of being retrenched. Even for leadership roles, the job is not secure, as evidenced by recent rounds of layoffs
In Singapore, because of labour crunch, NS and other social norms, the age line is probably not 35. However the day will come when a tech worker (SWE/DS/DA) find himself/herself difficult to find employment, probably at the age of 40-45
In workplaces, as you age you will also find fewer and fewer people older than you. There is certainly some rationale of preferring young workers: in a fast changing domain, older workers just do not have that much time and energy as compared with young ones
As individuals, do you actively look for alternative path? What is your strategy in response to the inevitable retrenchment?