@happymoep – unfortunately, you are misinformed. For just one example, Perlin noise is 0 at all grid points by design. It is also designed to be amenable to tiling – which is alignment repetition.
There are many related questions on the Processing forums about how to create seamless tiling with 1D or 2D Perlin noise – which is possible. You have the opposite problem – you are seeing artifacts related to repetition, and you don’t want them. One method of avoiding this is to stretch your sampling to fit within your period / octaves ratio.
the ratio of period to octaves that gives you a repeating pattern. In 2D, it creates a “tile” that seamlessly matches its neighbors; in 1D it creates a wrapping line (or a circular outline). Here is an in-depth discussion of how noise settings affect the way that Perlin noise repeats: tiles - How do you generate tileable Perlin noise? - Game Development Stack Exchange
from: How to close a "noisy" circular shape? - Processing 2.x and 3.x Forum
Keep in mind that pseudorandom generators are pseudo-- they often have strong repetition artifacts, even when this ISN’T by design. Classic Perlin noise implementations do repeat by design in a range dependent on their period / octave settings.
see also: java - Perlin Noise function returning same results for different inputs - Stack Overflow