It's not your screen. The GT4 Merc has a square DDU but the software it's running is usually seen on a wider aspect screen. Compare the Merc's DDU to that of a 2016 DTM car.
Do you mean this? It's not the fonts, it's the whole dash squeezed. I guess the real AMG GT4 has different graphics on its dash, but we don't have it in the game so the devs had to use one of the dash graphics they have and this one has to be squeezed.
You might want to watch your language as I believe it's against the forum rules. On another note you might have to wait quite some time until this is "fixed". The story goes that the dev that originally programmed the dashes for RaceRoom in some old/obscure language (I forgot the name of said language, sorry) has left S3 with nobody left with the knowledge to continue the work with it. This is why we see a lot of copy/paste dashes that sometimes don't even look similar to the real ones in RaceRoom for quite some time now. So either they hire somebody new with the apprpriate skill or have somebody from the team learn this language or make all dashes new with another language that is more common nowadays. I neither know which of these paths has been / will be chosen by S3, nor do I know how far any efforts in this regard have advanced until today. So this could be "fixed" in a month or a year or maybe never.
If proportions are an issue, the devs can change them a bit more. Before: After: I increased the width and decreased the height of the dash screen. The graphics still look a bit squeezed, but not as hard as before.