I just looked it up and there is a picture from an analysis where they are showing its possible state before the restoration:
https://media.springernature.com/lw685/springer-static/image...
"In UV fluorescence, the natural resin varnish layer fluoresces greenish, and areas retouched in 1994 can be distinguished from the original paint as they appear darker"
The full paper: https://www.nature.com/articles/s40494-019-0307-5
I just looked it up and there is a picture from an analysis where they are showing its possible state before the restoration:
https://media.springernature.com/lw685/springer-static/image...
"In UV fluorescence, the natural resin varnish layer fluoresces greenish, and areas retouched in 1994 can be distinguished from the original paint as they appear darker"
The full paper: https://www.nature.com/articles/s40494-019-0307-5