I wonder if its pronounciation is something like /'tæ:k/ or /'taːk/ or something between them.
Is there any difference?
how should we pronounce "a" in "Tag"?
The pronunciation is taːk, I have no clue what could have confused Google Translate.
There is regional variation in the standard pronunciation. In Northern Germany, many people will pronounce this word as [ˈtʰax], whereas in the South, the pronunciation [ˈtʰaːɡ̊] may be more common. The prescriptivist standard pronunciation [ˈtʰaːkʰ] the others have mentioned is probably not much used in actual speech.