The simplest solution is the below one.
str = "0x00000000 7B 22 69 64 22 3A 36 35 33 30 36 36 33 7D {""id"":2133221}"
arr = Split(str, ":")
strID = Left(arr(1), len(arr(1)) - 1)
msgbox strId
However, If you still need a more robust one, try regex
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solved Extract Text from Response Body in Coded Webtest using vb