I observed this behavior in a dataset (https://www.geoboundaries.org/globalDownloads.html - ADM2 Municipalities dataset) with Polygon and Multipolygon geometries, where it appears that highlighting a polygon that "contains" a similar multi-polygon in the pickable map results in the multi-polygon being highlighted as well as the picked polygon element.
I observed this behavior in a dataset (https://www.geoboundaries.org/globalDownloads.html - ADM2 Municipalities dataset) with Polygon and Multipolygon geometries, where it appears that highlighting a polygon that "contains" a similar multi-polygon in the pickable map results in the multi-polygon being highlighted as well as the picked polygon element.