The real question is how a company accidentally steals something like that for a 4th time. (This was the 4th time they've been caught doing this).

https://www.thepopverse.com/gaming-marathon-bungie-art-stolen-fern-hook-destiny-2-trailer-gun

He’s glazing Bungie so hard I thought he was an actual Bungie employee lol. Bro’s crashing all the way tf out, he might need some meds or therapy or something.

How does one even accidentally steal a texture someone else made?

One could easily apply Hanlon's Razor to this. For example:

• Bob is a game artist. Bob has a folder on his desktop called "Inspirations", where he saves art pieces he finds online that he likes, and a folder called "Assets" where he saves things he's created for the game. Bob transfers to a new department in the studio, or quits, or is fired; either way, he returns his equipment to the IT office.
• Dave is an IT guy at the studio. Dave takes Bob's computer after he leaves the job, and transfers all of Bob's files to the studio's shared drive. Dave isn't an art guy, and doesn't know the difference between "Inspirations" and "Assets", and dumps them all into the shared drive in a folder called "Bob's Things".
• John is the studio's new artist, replacing Bob. John syncs "Bob's Things" to his computer. John assumes everything in this folder has already been cleared for use by Legal. John starts implementing the art into the game.

I used to be a pretty hardcore Destiny 2 player for several years. In that time, I've seen Bungie fuck up a lot of things. But those fuck-ups were almost entirely caused by somebody in the studio not playing close-enough attention to something, and details getting mixed up in the pipeline. I don't think anybody at Bungie knowingly put Antireal's art into the game. I think the more likely explanation is that there was a lack of oversight, and files that shouldn't have been mixed together, got mixed together.

It wouldn't even be the first time Bungie had something like this happen; there was an instance where a third-party studio that Bungie contracted to build a Destiny 2 cut-scene accidentally used artwork that was not intended to be in the actual cut-scene.

Not to suggest that any of this excuses Bungie for multiple cases of plagiarism. Obviously, they need to have stricter standards in place when transferring files between parties. It's a colossal fuck-up, but I don't think that it was a fuck-up anybody set out to commit.

How does one […]

This is the key element. I don’t think this is a case where a team collectively chose to steal someone’s art.

If the theft was deliberate, it was probably an individual, with how big these projects are it’s not hard to consider how that may have flown under the radar.

I could also see one team member collecting assets to serve as inspiration and another implementing them without realizing they weren’t created in house.

With how exhausting the current state of the world is, I could even see a burnt out employee tossing something together without remembering where the asset came from.

Not trying to excuse what happened, the original artist is definitely owed for this, but there are other potential explanations for this beyond intentional malice.

How does one even accidentally steal a texture someone else made?

The fact that you're asking this is almost like...maybe you don't know what you're talking about? And should defer to an actual creative who does?

First off, it is a famously non trivial problem to compare every texture to every piece of art on the internet. It is trivial to add a bit of impercievable noise to deliberately foil even the best reverse image searching methods.

I think you may be taking for granted the number of artists and the level of autonomy they are given over their craft for a project of this complexity.

It's actually more weird to me that you don't understand why this is easy for a single dev to get away with. This is what happens when a studio trusts its artists to create something. No one is excusing it, but stop acting like Bungie did it on purpose. There's no evidence of that. The only thing they're guilty of is making a mediocre extraction shooter.