We are seeing the same thing. We have a single texture_block that is used for a countdown. When we change the image every second using SetImage, we see a white flash for a frame or two before seeing the actual texture image.
Other Verse UI texture_blocks also have this white flash the first time they are shown. It seems like after a Verse texture is loaded into memory, aka shown in the UI for the first time, we no longer see white flashes when changing to that texture. But, if we remove these widgets from the player’s UI and then later added them back again, the white flashes appear again on first load/shown.
This issue rarely happens during a single player editor UEFN session, but is consistently happening when playing with lots of players and on island codes.