No. It just means that all local variables from the ambient scope are available for lookup inside the body of the lambda. Only if you refer to a name of an ambient local variable will that variable be captured, and it’ll be captured by value.
The “capture anything” shorthands = and & are just syntactic sugar, essentially, telling the compiler to “figure out what I mean”.
A formal reference from 5.1.2/11-12:
If a lambda-expression has an associated capture-default and its compound-statement odr-uses […] a variable with automatic storage duration and the odr-used entity is not explicitly captured, then the odr-used entity is said to be implicitly captured […]
An entity is captured if it is captured explicitly or implicitly.
Note that “capture-default” refers to [=] and [&]. To repeat, specifying a capture-default doesn’t capture anything; only odr-using a variable does.