Foliage is visually missing in HTML5. This is a new issue and does not occur in 4.19, I believe that it may be correlated to this issue here.
1. Sync and Compile QA Game.
2. Open QAGame in editor, and launch on to HTML5 > Firefox 64.
3. Open QA-Promotion.
4. Move to the end of the map.
Result: Foliage triangles are no longer visually apparent
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-61141 in the post.