Due to the outbreak of nCoV-19 (Novel Coronavirus) many Countries have imposed several entry restrictions. But these are quite confusing for a lot of people. Some countries allow transit through parts of China (like Shanghai) but some restrict transit even through Hong Kong/Macau. Philippines restricted passengers coming from Taiwan too, but I think that that was later changed.
Where can one find a list of such restrictions for all the countries, ideally a source that is updated frequently
https://travel.state.gov/content/travel/en/international-travel/International-Travel-Country-Information-Pages/<COUNTRY>.html
pages is a good resource in English about the rules of each country. For Bulgaria the emitted this alert that is listed among the other alerts.