https://immigration.gov.vn/
Thank you all for the interesting informations and it is clear that places can be different hence different assessments of Vietnam.
As for the visa retirement, despite my research on the official website of the Vietnamese government, it seems that it does not yet exist and the government, but there are legal studies from Vietnam that prove the opposite but and it depends on which country you are from.
The question remains open.
https://accgroup.vn/mau-don-xin-nghi-huu#googtrans(en|en)