oh, this is an actual issue (please open one!) with contour:
ERROR: Multiple colormaps found for plot MakieCore.Text{Tuple{Vector{Point{2, Float32}}}}, please specify which one to use manually. Please overload `Makie.extract_colormap(::MakieCore.Text{Tuple{Vector{Point{2, Float32}}}})` to allow for the automatical creation of a Colorbar.
p2 = contour!(ax2, x, y, z2, colormap=:roma)
julia> p2.
alpha color colormap colorrange colorscale
depth_shift dim_conversions enable_depth fxaa highclip
inspectable inspector_clear inspector_hover inspector_label joinstyle
labelcolor labelfont labelformatter labels labelsize
levels linecap linestyle linewidth lowclip
miter_limit model nan_color overdraw space
ssao transformation transparency visible
p2 doesn’t have plots entry @jules