Why are sizes fucked up for cycling clothing

Like if you wear a size M jersey you have to wear an XL bibs
L jersey - XXL bibs

I bought some thermal bibs from Vaude size XL paid 120$ confection number is 54.
They are tight. I can wear them but they are not comfy, definitely need them in XXL

Also interested in buying Tacx jersey and bibs
XL is 50
XXL is 52
XXXL is 54

So is the XL 54 Vaude the same size as the tacx XXXL 54 lmao
I'm too poor to not get it right the first time