What day wil finish support for Lubuntu bionic 18.04 ?
Lubuntu 18.04. LTS, will be supported until April 2021.
It won’t be before the actual release date in April when 18.04 was first released (April 26) but could be any day from then until the end of the month.
The date/time is usually provided in official ML announcements (which get repeated like was done with the fridge announcement I provided link to; that propogate, eg. the “Planet” tag at the bottom caused it to appear on Planet Ubuntu also) ; they apply to main Ubuntu and all flavors like Lubuntu.
Note: the EOL of flavors don’t get posted to the fridge except what has already been posted there 6 times now, ie.
Maintenance updates will be provided for 5 years for Ubuntu Desktop, Ubuntu Server, Ubuntu Cloud, and Ubuntu Core. Ubuntu Studio will be supported for 9 months. All the remaining flavours will be supported for 3 years.
So your answer is not before 26-April-2021, and the end of the month of April 2021; for Lubuntu Support.
You can use
ubuntu-support-status to view the status of your actual install. Packages on your system from the ‘main’ archive will be supported until April-2023 (same dates of month apply).