filtering flattened projection does not seem to follow projection rules

# Scenario
If we have an object like so:
```json
{
"persons": [
{
"name": "bob",
"addresses": [
{
"current": true,
"address": "132 Main Ave"
},
{
"current": false,
"address": "99 1st St"
}
]
},
{
"name": "linda",
"addresses": [
{
"current": true,
"address": "132 Main Ave"
},
{
"current": false,
"address": "99 1st St"
}
]
}
]
}
```
and the query:
```
persons[?name=='bob'].addresses[]
```
I get the result
```json
[
{
"current": true,
"address": "132 Main Ave"
},
{
"current": false,
"address": "99 1st St"
}
]
```
This seems to line up just fine with the documentation of [what a "projection"](https://jmespath.org/tutorial.html?highlight=projection#projections) is in JMES.
It is my understanding that Filter and Flatten are both types of projections. So if I then filter the flattened projection like so
```
persons[?name=='bob'].addresses[][?current]
```
I would expect this
```
[
{
"current": true,
"address": "132 Main Ave"
}
]
```
but instead I have to pipe the result to a filter projection in order to get this to work:
```
persons[?name=='bob'].addresses[] | [?current]
```

# Question / Issue
I would not expect that I have to first use the pipe operator in order to achieve that.
Why is it that the filter is not applied as a projection of each result of the flatten operation? Am I misunderstanding something about what is/is not a projection and how the projection algorithm is supposed to work?