This one's a head scratcher 🤔

Low spot on the trail. When it rains, mud pit.

Good point actually, that makes a lot of sense.
- Or there was a barrier of sort there before, but now there isnt anymore.
Oh, that's a good notion. My thought had been that it's a place where people often stop so it formed a bypass of sorts.
Found the hiker.
Hmmm maybe, but the left is on a slope. The real path is lower, why wouldn't the rain pool there?
Here's a baseless guess: someone dumped something big on the trail there for awhile and a path formed from the detour and never went away
- The real path is the one that floods. When it's wet, people use the desire path to avoid the puddle.
- It's hard to tell from a picture, but to me, the road looks higher and everything slopes down to the right.

The main path has a puddle there after rain. Source: British.

As another British person, that was the first thing I thought of when I saw the picture and I came here specially to make the same comment you did.
Australian here, same thought.
Uk too my thoughts were this is a regular horse riding route. Horses hate these paths and will move to the side making more

it looks like there could have been metal posts at these spots, maybe a fence to only let pedestrians through, and cyclists started going around

This was my hypothesis as well, but I didn't detect any position where a gate might have been. I'm quite sure the two spots you indicated are leaves.
- if you know the original location, maybe check on street-view / satellite views. Google Earth also has the option to check older footage
Those are just leaves. No local authority would leave twisted metal pole bases ready to slice people's heels. Surely...
- good point! TÜV sagt nein.

Could have been tree overgrowth that has since been pruned.

Not once in my life have I seen a tree walk down a path like this

I do not think in the mud puddle theory. There is a moat right to the right where rain would drain. There is also no depression for holding any puddle.

I think there is a depression in the treeline and grass and also slightly on the road. I would say that there has been a broken/bend tree/bush laying in the way for over a year and was recently removed. There is no debre left, as the grass was also cut recently by a machine that also could have picked up any leaves.

The desire to overtake

...wait this isn't secretly a minelaying tips community is it?

Maybe shared pedestrian & bike trail? Bikes going around people

I've been digging trails out of fire debris lately and when obstacles fall on trails, temporary workarounds can cause this sort of erosion.

That sounds like it must be a satisfying hobby/quest/occupation.
- Along with picking up mountain/gravelbiking/cycling past few years, yes, absolutely, one of the most gratifying accidental discoveries in my lifetime. I only started doing it because our local managing agencies left the neighborhood park a shambles. It was closed for quite a while. Wound up using my historical GPS data to retrace some favorite segments and now I'm hooked. I grew up outdoors in a big way but lived in cities for decades. Completely lost touch with this part of my soul. I'm currently clearing coyote trails so we can walk through the maze behind my mom's property so I'm now getting in at least a little walk every day. I see wildlife all the time. Can blather on forever about it.

If this is in the US I would guess the city put a giant flashing "Share the Road" sign there for a while and everybody had to go around.

It looks narrow down further so this would be a natural passing spot