Orbital error in TDX data


I am working with a TDX CoSSC product and I am checking for possible residual orbital errors in my interferogram. For that, I import the data in SNAP directly, which are already corregistered and I create my int removing the topographical phase with SRTM 1 sec (about 30m). To my understanding, in an ideal scenario, the resulting int should be flat except for residual orbital errors or changes in topography between the acquisition of the DEM used and the acquisition of the TDX data. Is that correct?

My question is, how would those fringes linked to residual orbital error look like? What kind of ramp am i looking for? Is this a right approach to identify orbital errors? Objective here is to make sure no errors are introduced in the next steps of the insar analysis