Sorry, I think my explanation was confusing.
I meant that there is a number of frames in which the thorn registers damage and another when it positions you back in spawn.
In the meantime it is possible to register more than one damage, being possible to lose up to three hearts at times.
It's as if the collision was still registering damage even after losing a life, making it possible to lose a large amount unnecessarily.
And in this it is also possible to pass a level, so it is possible to pass even taking damage from the thorns.
Perhaps disabling collision temporarily while not yet positioned, or just setting a variable where the player is immune to new registrations should resolve.
At level 6 it is easier to do this, when jumping between two thorns next to each other, more than one life is removed. I believe this is happening because of the lack of this delay.