it's yzncross
his twitch About has a cfg download, which has it in the thumbnails folder
https://drive.google.com/file/d/1NXfl4UMrSOIaSz9XseKtPszvl13z4wPf/view

https://clips.twitch.tv/SuccessfulCorrectPieOneHand-ZqxklUkZHSBMCDDY

https://clips.twitch.tv/WildHilariousWallabyTBCheesePull-41LRxskeTBdg20v9
https://clips.twitch.tv/RenownedHandsomeGoblinTBTacoRight-w1Kx1Dsml97xipaQ
https://clips.twitch.tv/QuaintCoweringRatMoreCowbell-e4fgACEt8I5Nw_Cx
https://clips.twitch.tv/GrotesqueLaconicMacaroniRitzMitz-HK27GdUtvBvYERwB

preloading won't work with custom models or particles. Viewmodel animations are one of its few uses

coincidentally a cfg.tf pack i downloaded last week actually did the same for sniper rifles.
I played a full scrim with it and got flashbanged multiple times because it was sniper v sniper on product.
it's the reason I instantly made a post here to tell ppl it's horrible

can't imagine how it'd be like to play w that for a long time

Figured I'd look for uses in 6s
(WARNING: Probably bannable. Definitely shouldn't be allowed for altering sniper rifles)

I'd not use this for scouts because it'd be a laser show
It doesn't work for sentries
Sentries have no weapon txt file. tf_weapon_wrench and tf_weapon_robot_arm are just the melee attributes

It works for heavy
tf_weapon_minigun has a "tracer_effect" attribute. red has yellow tracers, blue has green tracers

It does "not" work for snipers
Sniper rifles have no "tracer_effect" attribute. tf_weapon_sniperrifle, tf_weapon_sniperrifle_classic and tf_weapon_sniperrifle_decap are just copies of eachother. So the code for the classic's, machina's and hitman's heatmaker tracers are handled elsewhere.
However, in the screenshot, I added a tracer_effect line to the sniper rifle to see what'd happen.
It works offline! but once you join an actual server you get spammed with error particles. Do not use this. You might think "oh I can know where snipers are at all times now". Nope. It will flashbang you if you are close to ANY sniper, both enemy and friendly. And even at a distance it will block your view of the sniper by being very obstructive (and the sniper himself does not have that issue so you get shot at)

it's in the FAQ in the main post
(answer to the question "Help! It doesn't seem to work, or it's working sometimes but then stops working after I join multiple servers.")

https://i.imgur.com/2HhVbgq.png

https://clips.twitch.tv/MoistCorrectPeafowlAliens--OIjt6KT1i7Zkc_V

in case the download ever goes down I'll post an explanation:

the vpk contains a "materials" folder. In materials you'll find:
"healingtrail.vtf"
"softglow.vtf"
a folder called "smokelit2" in which there is "smokelit2.vtf"

All 3 VTFs are empty 1x1 images. VTFs are just images with some flags attached for source engine properties

the game attempts to reach this VTF. It does this by looking for a VMT file of the same name (a txt file that tells the engine how to handle a material). But there are no VMTs here, only the VTFs. So the source engine cannot load the VTF and replaces it with the default texture

I remember people asking about vouri's settings in the past.
iirc Vouri doesn't know himself what causes it? Could be wrong about that part though
Could ask him to make sure

Perhaps it's a broken old particle pack that's still in custom. Pugchamp servers allowed custom particle packs (like the one with the big green overheal cross). This could be a similar case.
Or a bunch of actual TF2 particles are missing

My guess would be a broken particle pack though considering stickies and overheals also have default textures
https://imgur.com/a/nwjk0ul

https://clips.twitch.tv/AcceptableGoldenHorseDerp-VEDzOJ1H1qM034X4

https://clips.twitch.tv/ExcitedSaltyQuailPMSTwin-KQTrq5e-l9n8dWvY
https://clips.twitch.tv/EphemeralSavoryCrabPlanking-hkogsXhWTufDEhGw

TF2 MMO incoming

https://www.dropbox.com/scl/fo/63fnj4o2pbb6jtr123qw4/h?rlkey=lajijuzfcjf2s3m8x2zw3n2zs&dl=0
I have one that looks like it
Probably the exact same size and length as that one
Though it's hard to tell because of 4:3 and bitrate