Orbital Periods and Drifting Satellites

[AlamoVampire]

Ok. I am completely stumped here. I have 4 Communication Relays <RA-100's> is what should be synchronous to each other orbits. All 4 are set to roughly the same orbital height <you will see their altitudes in the images, I cannot recall off hand, even though I just took these 4 pictures lol> but, the important part is, they are in temporal LOCK STEP at a period of precisely 1 hour 4 minutes 10 seconds EACH. They were roughly equidistant making a rough + sign in orbit where each relay was at the end of each segment of the + sign. I thought I was seeing drift in them as I was doing missions, and dismissed it as me just being jumpy. Turns out, I am seeing drift, and a whole heck of a lot of it. Is my save modded? Yes. Do I think that has something to do with this? No. Why? All parts on the 4 satellites in question are 100% stock parts. The only item in active use to have any mod parts on it is my science station Station 1 and its only got 2 parts from planetary base. Every other part that is in active use on ANYTHING aside from 2 corridor ends is 100% stock KSP <DLC included>. So, can someone who is far smarter than I am at orbital maths please tell me why 4 satellites in IDENTICAL periods at roughly the same orbital height +- 15-20km at MOST on either side what was intended are drifting THIS badly?

When I finished launching this 4 satellite array up, number 4 was across from 2 and 1 across from 3, but now? well, I think the images speak for themselves. I have no idea what happened. Not a single 1 is in orbit with any kind of engine on it. All drives were dumped once all 4 were in orbit and I was happy with where they were. Yes, they have RCS, but, despite what the pictures state, they have all been shut down at the blocks themselves. Besides, I dont think RCS is capable of triggering this kind of drift w/out seriously altering the orbits themselves. Am I just glitching or is there something else at play here? 044802102025

[AlamoVampire]

Does anyone know why 4 satellites with nearly identical orbits with identical orbital periods are drifting as shown above? The only thing I can figure is altitude is a factor but im recalling someone saying as long as periods match it shouldnt matter. Please i beg help me understand. 202302102025