Sorry about potentially sideways pictures!

I have 2 box balls either side of my front door, both grown from cuttings for the same parent, maybe 5/6 years ago.

The first image, the ailing one, has appeared 'different' for about a year after 5-6 years growing identically. I swap their positions every 2nd year or so. The leaves are deeper green, shiny, more, maybe 'brittle-edged'- not perhaps 100% 'healthy' when compared to the healthier one, which is blooming (as it were). New growth is consistent vibrant dark lime-green.

This issue has appeared in the last 2 weeks.

Do I have box blight?

And yes, I know what to do with the plant and soil, but what shall I sluice the container with to free it of that fungi/virus so I can start again?

Am sad as I grew both from cuttings 12 years ago!