Don't forget that whilst Ubuntu 20.04 LTS has five years of community support; Ubuntu-MATE had only three years, and is already End of Life.
Thus your Ubuntu-MATE support has already ended.
Your Ubuntu community support will end (ie. sites like askubuntu.com etc) after 5 years, or 2025-April for 20.04 LTS.
The ESM or extended support comes from Canonical, not the Ubuntu community.
What support you obtain from Canonical will depend on your contract, ie. email, phone etc, as the basic options include only security fixes but no actual support.