I suspect there are several problems going on at the same time here.
Note how on this bit, the b+f between the left sprockets next to the empty bit of image area is lower than in the section below it where there is a partial image. This can only be explained by a lack of development in that area. Note that development did take place on the opposite side, where there are edge codes and higher b+f. A similar pattern here:
What's interesting is how the undeveloped area is offset along the edge of the film, creating a C-shaped form. Also note the width of this band; I have the impression that it gets narrower towards one end of the roll.
There seem to be about 1.5 frames that came out okay, then half a frame is a pink line, then 3 frames greyed out, as if they didn't receive any development chemicals.
Well, none of the frames look OK to me, but the ones that are quite dense may just be badly fogged and underexposed at the same time. The pink line is basically undeveloped (see 'C-shape' above). The lighter frames are developed alright, but less so than the others.
Note that you can use the length of these artifacts (no. of frames/sprockets) to figure out how large the diameter was that the film was rolled up on, which can then help determining at what point it happened. Doing this, I come to a roll diameter of around 70mm, which is in the ballpark for a regular processing reel. I also notice that the diameter is larger on the clipped end and drops away, which means that the clipped end went onto the reel last; I assume this is the end where the film was cut from the cassette during loading it onto the reel.
Then there's e.g. this bit:
Note how there appears to be fogging in particular around the sprocket holes. It's unclear what may have caused this; fogging around sprockets usually points towards problems with light leaks in the camera on the take-up spool area. But this is usually associated with higher degrees of fog in the image area than what we see in this bit.
This is interesting, too:
There's an unprocessed bit on the top edge, left, which you often get on properly spooled film in a hand tank. There also appears to be severe fogging around the sprockets, but interestingly not (or less so) in the image area.
There's also this:
Note the irregular frame spacing. I'd be inclined to check other visible frame spacings to see how much variation there is, and especially if there are overlapping frames. This would suggest camera failure. IDK how this particular camera counts frames, but if it's an optical (IR) system, this could be a hint w.r.t. possible light leaks.
One thing this reminds me of is trying to develop film on a rotary base, with the rotary base not having done its work - i.e. the tank sitting horizontally. This does not quite explain the entirely undeveloped band (I'd have expected to see some very faint development there), but it could explain the alternation between strong development and weak development. The apparent fogging around the sprockets can be explained by the developer remaining stuck there due to capillary forces around the sprockets and the reel slots even on the part of the reel that sat above the processing liquid.
@dearcomposer can you give some details on what kind of processing equipment (tank, reel, and rotary base/machine, if any) you used?