I got a postdoc position at age 34 years in China. My documents are verified and I got the invitation letter. My employer applied for a work permit which is in process. I am waiting for that to apply for Z visa. But it is delayed due to the Covid-19 pandemic and travel ban. If it is delayed further I will be more than 35 years which is supposed to be maximum age limit for postdoc. Can I still get the position?
In general Chinese universities are rather ageist, and treat age restrictions very seriously. It is likely that you would not get the position due to your age. However, there are many workarounds you can discuss with your potential advisor, such as getting a position as a 研究员 or 副研究员 (like a staff researcher or staff scientist) that don't have age limits, but also might not have the federal government salary support that foreign postdocs are eligible for in China. You would have to discuss with your potential advisor to see if such an option is available to you.
Having said that, the pandemic changes the rules for everything, so there is a possibility that in this special circumstance an exception might be made, you'd have to discuss with your advisor and see how willing they would be to spend political capital to secure the exception for you.
It is the University that has the age limit, not the Chinese government who issues the visa. For example, the postdoctoral research fellowships offered through the PIFI scheme at the Chinese Academy of Sciences have an age limit of 40 years (current announcement).
If your employer is still offering you the position, and you don't have other reasons you would be rejected for the visa, I expect it should go through.