When your new designs start looking similar to ones that you’ve seen or made earlier, your design process is suffering from Bounded Rationality. You need to make an effort to change it.
While designing a new product, a designer is likely to apply functions, features, layouts etc. similar to the products that they have already designed or seen. To avoid this, you should first take time to design the known concepts quickly. You should then use the creative process to start again from scratch and design with a fresh mind. When you understand the users deeply and let the design flow based on the user understanding & process, you’ll no longer be bound by the already known concepts or bounded rationality.
While designing a new social media application, most designers would draw concepts from existing social media apps. This will not be a completely creative design, unless designers start thinking fresh.