You might want to follow this: Ubuntu Mate LTS with 5 year support?
It looks like a 5-year support is not tenable, in current circumstances (that is, for free). But my suggestion is to have that possibility against a fee, as it is for classical Ubuntu beyond 5 years.
To those who will download Mate 20.04, I suggest to make a donation when offered to do so (https://ubuntu-mate.org/download/amd64/focal/thanks/). Think of what you would pay for an iOS or Windows installation !!