I'm not sure exactly as it might be a very specific or even fan - made story. But generally, in the Shrek series, Shrek goes through various adventures, often dealing with his relationships and his identity as an ogre. Maybe in this part 3, he could face new challenges in his marriage with Fiona, or new threats to his home in the swamp.
In the German original, Rapunzel is portrayed as a rather innocent and naïve girl. She has been locked in the tower for a long time, so she is somewhat sheltered. When the prince comes, she is easily charmed and falls in love quickly. Her long hair is not just a physical feature but also a symbol of her captivity and later, her connection to the outside world.
Kind of. Shrek shows a unique take on love, with the characters overcoming obstacles and discovering their feelings for each other in an unconventional manner.
Rapunzel is definitely not true. It belongs to the realm of fantasy and folklore. Tales like Rapunzel are often used to spark the imagination of children and adults alike, but they have no basis in reality.