Max ash in DPF?

Saw a question on DPF just now, and thought about something I've recently noticed on my car.

I've been using VAG DPF since 2016 on and off. Recently the oil ash residue box shows (gm) instead of (l) - which I never knew what it represented - possibly litres?

The car is up around 125k, mostly urban driving - although a recent re-gen occurred over 300 miles, and another over 250 miles.

The other thing is CFHF engine type is still not an option - set to read from ECU.

My question is, has a definitive max ash level been established? I know it's not space capsule instrumentation and there are many variables due to driving use/manner etc. I love the car so much and I'm of the old fashioned view that it is cheaper to repair rather than sell a good car and buy another at much cost. It would be nice to have a view for my OAP budget 😨