I don't know about whether 这种裁员很常见吗, but your company is very
uncommon.
It sounds more like the former "ICC"s but your company actually pays you the
wage when you are be trained and not generate billable hours.
Also, if it takes 6 months to get familiar with the company's system (I
suppose it is quite proprietary, so much so that non-company people can't
learn before the job) when would they let a well trained employee go after
just 2 years?