https://opendata.laquintaca.gov/maps/cbb70feb1a5b41b3928577b9d54688de/explore?location=33.653444%2C-116.241249%2C12.54
Even the ESRI default is indexed,
you should always use flat.
ESRI want to save their hard drive space by leting you use indexed when you publish it on ESRI's server. Indexed will omit lots of detail tiles resulting a small size of tile cache.
You have large hard drive, no reason to save you hard drive space. The best choice for you is select "flat", which will remain all level of details resulting a larger tile cache.
https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/create-vector-tile-index.htm
https://enterprise.arcgis.com/en/portal/10.5/use/publish-vector-tiles.htm