At one of last Blender conferences, the founder (and at that time CEO) gave some insights about funding and compared it to Thunderbird. https://youtu.be/VZ5022VaMmA?si=m1hD9wEQ16s8Zu3b&t=1297 ;
Fore More recent numbers: In 2024[1] (last info I found), Blender had 3.1m € in donations (600k more than the year before) and Thunderbird had around 9m € [2].
I kind of get it, Blender is way more niche than Thunderbird, but imagine what they could do with even more money.
[1] https://download.blender.org/foundation/Blender-Foundation-A... on page 76 [2] https://blog.thunderbird.net/2025/10/state-of-the-bird-2024-... I did the money conversion based on today's exchange rates