The Ebenholz burn damage bug is fucked up because it looks to me like he's not only going burn damage but necrosis at the same time, judging by how the deathveil assassin just falls over after dashing past Degenbrecher.
I actually think it's just necrosis and the icon is specifically messed up not the actual damage type. He does the same damage with the debuff/full charge blast regardless of the icon showed, and the difference would be pretty pronounced with both stacking (both due to the extra 7k elemental damage and the further reduced res). Also you don't see it here but I can confirm the necrosis enfeeble effect still applies from earlier attempts where that was key to the strat at that point (and it showing burn gave me a heart attack because I assumed Degenbrecher was about to explode lmao). Still, very weird! I think it must be related to the specific assassin enemies or this stage in particular, as I've played with this team for years now and never seen this happen anywhere else, but I'm not really any closer to a definitive answer as to what exactly causes it. Esp since, while this was repeated in various attempts, it wasn't always on the same assassin, so everything else my units/the enemies were doing was different and it still triggered??