I worked on a very large airport project years ago where every drawing had 179k registered apps. It infected the entire project and every drawing (over 100) had this issue. I spent two weeks fighting it and trying to figure out the source. I narrowed it down to the road designers and when they used AutoTURN in the main proposed based drawing. Every time they worked with AutoTURN the main proposed base got infected. Since that drawing is XREF'd into almost every other drawing, it spread like a virus. I told the roadway group to keep the AutoTURN stuff in a separate drawing, but they didn't listen and it kept getting infected.
Good luck tracking it down. You'll need to do a batch purge using that tool to remove them from every drawing as they get brought into drawings through XREFs and blocks. Even if you purge a drawing, but an XREF still has it, as soon as the drawing is opened again or the XREF reloaded it'll bring the REGAPPS with it.
C3D 2024-2026
Windows 11
32GB RAM