European quotation marks commonly have the left one down low and the right one up high. The same applies for single quotes. But using comma-backtick is deeply unorthodox.
The French use « », Italians use ‘regular’ “quotes”, etc.
Strangely enough, this is the first time I see your style of quote, in two decades on the Internet.
Wouldn't say it's "common", because IIRC that's only the case in Germany and Austria.