Although alstroemeria get by with a low-water program, the plants look like they are too dry.

Appears that you have the low growing forms - some years ago,

I had some of the Princess series years ago in SoCal which grew to 12 inches max. The taller forms flowered better for me than did the Princesses.

It doesn't look like lack of water to me. It looks more like a fungal disease. Note that even last year there were yellowing distorted leaves. Can you show a close up of some affecpcted foliage?

The plant also looks like it sure could benefit from division and also possibly having the soil enriched ... and, yes, it does appear to have some type of foliage blight.

Doesn't look pathogenic to me. Look more like cold damage or possibly chemical burn. And the yellowing leaves on last year's photos look more like mechanical damage or just aging than anything else.

Not much affects alstroemerias.....a couple of root rots can be common but only if planted in poorly draining soils that become periodically water logged.

I first thought it was some sort of herbicide drift.