True, but planting trees as a method for carbon sequestering is not a novel idea, and currently seems one of the better short-term options. Long term it's not that great for the reason you mentioned, and there is quite a lot of debate about it going on right now.

https://science.sciencemag.org/content/365/6448/76

https://www.nature.com/articles/d41586-019-00122-z

for two more or less competing views.