clang-format incorrect formatting of proto files

Question

Using clang-format 17 with the following .clang-format file:

# other languages ...
---
Language: "Proto"
BasedOnStyle: Google
UseTab: Never
TabWidth: 4
LineEnding: LF
InsertNewlineAtEOF: true
ColumnLimit: 120
IndentWidth: 4
ContinuationIndentWidth: 4
BreakBeforeBraces: Allman
AlignConsecutiveDeclarations: AcrossEmptyLinesAndComments
AlignConsecutiveAssignments: AcrossEmptyLinesAndComments
AlignTrailingComments: true
SpacesBeforeTrailingComments: 1
...

I get the following:

message AssignUserTickets
{
    int64    user_id                               = 1;
    int64    ticket_type_id                        = 2;
    optional google.protobuf.Timestamp expires_at  = 3;
    int32                              num_tickets = 4;
}

When the expected result is:

message AssignUserTickets
{
    int64                              user_id        = 1;
    int64                              ticket_type_id = 2;
    optional google.protobuf.Timestamp expires_at     = 3;
    int32                              num_tickets    = 4;
}

Removing the optional keyword gives the desired formatting, but we don't want to do that¹.

How can I achieve the desired formatting without changing the message definition?

---

^{1 I know that optional is not required in this case, since Timestamp is a Message and therefore has explicit presence by default, but we still want to use it for consistency with simple types and as documentation to the user of the protocol that omitting it has specific meaning.}