Is there any design? It's just the flag and a title + subtitle.
Also, the EU is the most efficient government in terms of overhead, and having seen some of it up close not wasting time or money on "unifying design languages" for every single funding billboard is very much EU style. Just copy-paste by some local authority in Powerpoint in most cases, I bet.
What are the funding billboards for, anyway? They're an eyesore, and it's all paid by us EU taxpayers anyway. They should say "financed by you", or better yet, not exist to begin with.
Looking at the modern iterations of the program guidelines for these programs, especially [1] and [2], you basically have to use the flag, the text over, under or to either side of the flag (your choice) in one of 6 fonts (Arial, Auto, Calibri, Garamond, Tahoma, Trebuchet, Ubuntu or Verdana), and have some rules for minimum distance, minimum size and proportionality. They absolutely could have made those two match visually. But each program offers premade banners that match the design criteria, and those don't always harmonize. As you say, nobody cared
1: https://hadea.ec.europa.eu/programmes/connecting-europe-faci...
2: https://commission.europa.eu/document/download/3192a0ef-6bda...
3: https://ec.europa.eu/regional_policy/information-sources/log...