Is this fungus or something else?

[Notcopingwellhere]

Hi there- can any clever gardener tell me what’s wrong with these leaves? I had some fungus fighter already so have sprayed that on but don’t know if I am barking up the wrong tree! Thanks.

This is the whole plant.

Some plants with leathery leaves do have a dusty coating on their leaves naturally, are you sure it isn't that?

Thanks for replying’ I don’t think so because there are other leaves that are not affected at all.