Courgettes on their way out?

[Shadylane]

We've got two varieties, a green un and the yellow F1 Taxi (I didn't realise it was an F1 at the time). They've produced well but seem to be slowing down (not that I mind) and while the leaves look healthy the yellow ones are getting green spots on them (on the fruits) and are slightly misshapen. I remember this happening last year with a yellow one that someone donated to us. I naively thought it might be crossed but seem to remember seeing something somewhere suggesting it might be mosaic virus.

We ate the fruits last year and didn't die so assume they're safe to eat. Can anyone with similar experience confirm my suspicions?