Destroyed resonators visually remain on portals
This happens very often and hasn't been fixed since at least Umbra anomaly.
On the screenshot you can see a few neutral portals which look like they have resonators deployed on them (of course they don't since they're neutral). The phantom resonators remain even after poftal capture, and that makes it difficult to see which resonators are actually deployed on portal and how many of them there actually is.
2.59, Android 10, Samsung S10e