That amount of money a month is extremely substantial for an open-source project, and especially for a non-corporate distro. It also far exceeds previous years.

The pressure mostly seems to be from adding wayland support to Cinnamon, combined with perhaps maintaining more projects at too regular an interval than their team can chew.

Might want to read the article first. Mint has received more donations last month than any on record for them, $47,000.