Funny, I've been out of the forums for weeks and today I come back only to see this thread on the first forum page. What a coincidence!
I kind of doubt that it's a crossover. Instance is an instance. Why would something leak between two separate instances like this? How would it be possible to produce this kind of bug in code? We don't see anything else leaking from other instances.. ?
I still think that it's the thargoids. I haven't seen anyone solving this or give a solid proof that it's a bug (or thargoids for that matter, yes). I think it just maybe something added to the game to give a bit of a spooky feeling to a player but nothing more. A bit failed feature because everyone is so convinced it's a bug

And I'm not saying I'm 100% sure it's the thargoids. But I choose to believe its them.
I've seen some other things in Maia too but I haven't posted them here because people find it so trendy to call all the videos clickbaits these days. I was heading to Obsidian Orbital few weeks back and I was searching for Unknown signals, looking at the stars. I saw a glowing dot moving around the Dwarf star near the orbital and changing a course like another ship and dissapearing. There were no players or other ships in the area. Just the glowing dot coming, turning and going away. And this all happened in supercruise. Crossover bug? Maybe, I'm not a coder. But I think they are made to spook people out.