Contrast issues in public signage

In the Paris metro I witnessed contrast issues in public signage.

Have a look at this photo. The sticker informs passengers about on-going building works in station Châtelet - there at the time being (Jan 2018) no possibility of interchange to line 4.

The sticker blocks the light coming from the translucent display, and the contrast makes it very hard to read. (No problem when applied to non-translucent displays, though.)

The image also obliterates the adjacent station name Les Halles.