these patterns mostly come from temporal decorrelation. Please have a look at the explanations in this post Some explanations about concepts of fringes of interferogram and coherence
As you are opening quite much topics recently: Please try to use the search function, read a bit about the basics of radar imagery (two excellent materials #1 and #2) and try to put remaining questions in existing topics to help keeping this forum clean.
Phase information is very sensitive towards rapidly changing surfaces (canopies, lower vegetation cover). Unless you have a bistatic system (two images at one time) you cannot avoid that some areas in your interferogram will not contain proper fringes.