Was it seasonality or the algorithm?

I first blamed seasonality, algorithms and my niche, but the real cause was my own coverage.

What was the real problem?

A coverage problem. My content spoke to one exact phrase, not the topic around it.

How did I find the gap?

I sorted by impressions, not clicks, to see what was not showing up at all.

What did I notice on re-reading?

The same two or three phrases, repeated over and over, with nothing wider.

How big was the gap?

My best pages triggered 100+ queries. My weakest triggered 12.

Was more content the fix?

No. Widening my understanding of the same topic was the fix.

Where can I read the full diagnosis?

See exactly how I found and fixed this on my own site.