Starting from 23 May morning(Beijing time), lots of Samsung phone users in China suddenly experienced system crashes and couldn't use the phone anymore.
The symptoms the users saw were that the phone started to restart infinitely and the screen turned into dark screen and nothing can be done to get it recovered. Based on the reports, the impacted models include Samsung Galaxy S8, S9, S10 and S20 series, Other models don't receive many reports yet.
After receiving the reports, Samsung China responded on Weibo that an investigation is undergoing and the mitigation plan will be released as soon as possible.
There is no official solution for this problem yet. But some people did some test and found that it might be related to a system update happening today and the Calendar app update where the time was wrongly calculated and hence caused the system crash. The immediate proposed solution is to disable system auto-update until an official answer sent by Samsung.
Samsung A50 also show this problem...