Ecosia uses planting trees as the poster child, because that's what people want to hear. But in reality, there's a lot more going on. Ecosia produces 200% of it's estimated energy footprint in solar. They also protect forests, and help populations in Africa with their forests and with adapting to a life without deforestation.
Thank you, I was about to point that out as well. Ecosia advertises with "we plant trees" because that is what people understand and want to hear. Under the hood, there is a lot more going on. Ecosia does not only support one but multiple projects with a variety of goals, including reforestation, preservation etc.
What's also nice is the fact that their are extremely transparent about their finances. They are a registered non profit in Germany and they frequently publish their finances and other insights, which is always extremely interesting