I confirmed as well - with an empty Community folder and running in safe mode, they are still there. Also deleted rolling cache. You have to fly close to them for them to appear, but they’re definitely a Sim issue and not RTMM, Orbx, I-love-VFR or any other addon.
Bug report opened:
https://forums.flightsimulator.com/t/bizarre-obelisks-in-alaska-north-of-pajn/566822?u=flyerdreamernj