Microsoft is following a cadence where it has announced the release and end date of the .NET Core framework and .NET Core versions.
Microsoft has strongly conveyed its message that Microsoft will no longer be providing any support to any of its users if they reach them for any help with the .NET Core 2.1 version or any older version to it.
Microsoft has also announced the new launching of a new version whose release and end date are also mentioned accordingly with its support period. It offers 2 support methods that are EOL and LTS. LTS usually comes with a minimum of 3 years of support and EOL for less than that.
Before taking any decision, you as a business owner and a developer should be aware of the upcoming versions and their end date for their support. You can gain more knowledge by reading the blog written in detail with the exact release and end date announced by Microsoft itself.
For more details check the main source - Microsoft announces end of .NET Core 2.1 support