Update from the 30th of January 2022
That is what I thought back then. Cryptocurrency was booming and using it for good was a refreshing take for a change. Today, this model would not work anymore since browsers block cryptominers and restrict background processes. Plus, it requires insane amounts of computational power to produce a significant enough amount of cryptocurrency so that it would help in any way. The costs incurred outweigh the gains: electricity, environment, hardware. Even back then, it was difficult to prove whether the people behind DonateYourTab could be entrusted with this responsibility.
If you want to donate money to charities, do not donate your tabs, donate a sum you can afford.