Help to identify what is killing my herbs

[vgalaron]

Hello,

9 months ago I planted some oregano plants that have been looking great through the winter, but suddenly the oregano plant and the flowers that I had closer to it have died.
I removed them and planted new flowers and basil this time, and they are not looking good either...
In between them I have some geranium and thyme that are looking good, but I'm a bit worried something odd may be going on in the soil, because the thyme is also starting to look a bit odd.

Could you please help me identify the issue?

[cazza]

Is it damp where they are planted? Looks like some sort of root rot....

[Bruzzybill]

Looks fungal