I can’t find KDE’s financial report, but in a video I watched it was claimed that Thunderbird collected more donations than KDE. It seems quite hard to believe, but in 2022 Thunderbird collected more than 6,4 million dollars.

KDE is an entire desktop environment, with a bunch of applications and even partnerships that have yielded a KDE laptop. Should Thunderbird have been able to collect more money than KDE itself, there might be something that KDE can learn from Thunderbird.

Edit: Added the link to the video that I watched