Unexpected collision behavior after adding mapbox-terrain-dem-v1 (hidden symbols with ZoomLevel >=15.0 )

[WernerMairl]

Hi
not sure if this is a bug or a wrong understanding on my side ;-)

Situation:

I have a map with a (self implemented) vector source for point features.
I'm using a symbol layer to show maki symbols (Points of interest)

I get a unexpected behavior, in the moment when I set the terrain to mapbox://mapbox.mapbox-terrain-dem-v1

Using the terrain features HIDES all my symbols on ZoomLevels >= 15.0
Without the terrain feature I can see my symbols until ZoomLevel 22.

Using the "showCollisionBoxes" feature on the map, it looks like the symbols are not visible for some collision!
Bug ? Feature ?

Any way to workaround this ?
Collision properties for symbols and labels seems NOT helping in this case (smoketestet)

3.9.2 and older:

Chrome, Safari:

Thank you in advance!
Werner