What can cause the splotchy highlights seen on this image?

Close up:

Film: Efke PL100 shot at box speed
Development:
- Ilfotec HC 1+31 in MOD54/Paterson Tank
- Kodak Indicator Stop Bath
- Kodak Rapid Fixer
- Kodak Hypo-Clearing Agent
Hung in drying cabinet
Negative surface looks smooth, no physical build up (i.e., dust)
Density is visible in the emulsion (negative has dark patches in central area)
This is the first time I've used this film. Other negatives have similar splotches, but their location is not identical, just that they all fall within the central area of the negatives.

Close up:

Film: Efke PL100 shot at box speed
Development:
- Ilfotec HC 1+31 in MOD54/Paterson Tank
- Kodak Indicator Stop Bath
- Kodak Rapid Fixer
- Kodak Hypo-Clearing Agent
Hung in drying cabinet
Negative surface looks smooth, no physical build up (i.e., dust)
Density is visible in the emulsion (negative has dark patches in central area)
This is the first time I've used this film. Other negatives have similar splotches, but their location is not identical, just that they all fall within the central area of the negatives.
