Daffodils

I "think" it can be due to overcrowding of the bulbs, causing them to come up "blind". The clumps need to be dug up, split and replanted with more room to grow.
Of course. I could be making this up!!

EDIT = I was partly right..........https://www.rhs.org.uk/problems/daffodil-blindness

It is overcrowding for some of the clumps (over 40 years old and never been touched) but a lot of them are reasonably spaced which I think is a different cause. One thing the RHS site mentioned was water logging which has been an issue here the couple years and I think was responsible for a healthy apricot and climbing rose suddenly dying in the side garden, an area of about 30yds x 20yds.

I'm not sure what to do about it as it can also threaten to flood the house. When the ground is saturated, water can run off it and down the drive onto our patio. Twice it was up to the level of the our patio door. The first time it happened, I bought a dirty water pump and was able to empty the patio onto the roadside where it ran down the road and away.  The soakaway for the drains is in the side garden which could be less efficient now after 40 years but I'd be loathe to dig a new one if it would not make any difference. A new soakaway may well work as I remember now that I just dug a big hole and filled it with rouble but it wasn't lined in any way except for polythene on top.
The patio in fact is the lowest point for quite an area as all the surface drainage and house gutters front and back lead to the soakaway and are also able to empty into the patio if it slows down.