This is exactly why on most phones you can turn this feature off, which is also good to know.

If you are really really curious, you can find a phlebotomist that is game and use your own blood. This is the most ethical way to get some cooking blood and it can be done. (For proof see article)

https://www.vice.com/en/article/i-made-meringues-out-of-my-own-blood-and-ate-them/