Size function does not work with pairs(::NamedTuple)

The size function works as expected for pairs(::Array), but throws an error for pairs(::NamedTuple). Is it expected or a bug? Shouldn’t the functions on Pairs work uniformly for all underlying containers?
If it is a bug, how can I open an issue?

julia> VERSION
v"1.5.0-DEV.338"

julia> A = [1, 2, 3]
3-element Array{Int64,1}:
 1
 2
 3

julia> d = pairs(A)
pairs(::Array{Int64,1}) with 3 entries:
  1 => 1
  2 => 2
  3 => 3

julia> size(d)
(3,)

julia> A = (a=1, b=2, c=3)
(a = 1, b = 2, c = 3)

julia> d = pairs(A)
pairs(::NamedTuple) with 3 entries:
  :a => 1
  :b => 2
  :c => 3

julia> size(d)
ERROR: MethodError: no method matching size(::Tuple{Symbol,Symbol,Symbol})
Closest candidates are:
  size(::Tuple, ::Integer) at tuple.jl:22
  size(::BitArray{1}) at bitarray.jl:99
  size(::BitArray{1}, ::Integer) at bitarray.jl:103
  ...
Stacktrace:
 [1] size(::Base.Iterators.Pairs{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}}) at ./iterators.jl:232
 [2] top-level scope at REPL[154]:1

pairs is an iterator and its support for size is accidental. Use length.

See https://docs.julialang.org/en/v1/manual/interfaces/#man-interface-iteration-1