Freezing Tentacle Fiends causes these big ice balls to be drawn on the screen.

Ref. number: 3 642 995 772

https://imgur.com/a/tZgF7hq

The graphical anomaly expires when the Tentacle Fiend dies.

Using:

Frost Blades
Hatred
Herald of Ice
I have an additional 9% chance to freeze on my shaper ring if that matters.

Edit: Also using the Vulcan beta renderer.

I don't recall this happening in EVERY elder influenced map. But at least in Sunken City and Spider Lair to name a couple. I don't remember where the last image was taken from... maybe Spider Forest?


Edit:
I just cleared an Elder influenced Laboratory map, where this bug did not occur.
Map mods:
Inhabited by humanoids
monster skills chain +2 times
Unique boss deals 30% increased damage
unique boss has 36% increased attack and cast speed
influenced by elder
occupied by enslaver
map has 15% quality
monsters gain a frenzy charge on hit
players gain 61% reduced flask charges
players have 30% less area of effect
126% increased quant
61% increased rarity
+39% monster pack size

Edit: Bug occurred again this time in Belfry map.
Mods:
increased monster variety
cannot leech mana or life
+49% monster phys dmg reduction
influenced by elder
occupied by enslaver
monsters cannot be taunted
monsters' action speed cannot be modified to below base value
60% increased quant
35% increased rarity
+23% monster pack size

I've reported this 2x. happens with freezing pulse totems as well, seems to just be the tentacle fiends. Would appear to not be much of a priority for GGG as there has been no response or acknowledgement. Don't really blame them as its not breaking the game and they have plenty of other issues to fix.
I also use vulkan and that might also make it less priority.