I have some TMS layers in MapProxy that I reproject from GLOBAL_WEBMERCATOR to GLOBAL_GEODETIC as follow (all of them using same configuration so I'll show only one):

Source:

      opentopomaps_tms:
        type: tile
        grid: GLOBAL_WEBMERCATOR
        url: https://b.tile.opentopomap.org/%(z)s/%(x)s/%(y)s.png
        transparent: true
        request_format: image/png
        concurrent_requests: 5
        http:
          client_timeout: 600

Cache:

      opentopomaps_cache:
        grids: [GLOBAL_GEODETIC]
        sources: [opentopomaps_cache_in]
        disable_storage: false
        link_single_color_images: true
        concurrent_tile_creators: 4
        format: image/png
    
      opentopomaps_cache_in:
        grids: [GLOBAL_WEBMERCATOR]
        sources: [opentopomaps_tms]
        disable_storage: true
        link_single_color_images: true
        concurrent_tile_creators: 4
        format: image/png

 

Layer:

      - name: gebco
        title: GEBCO Batimetry
        sources: [gebco_cache]



My problem is: when I'm before scale 1:35M the map seems not reprojected. Here are some examples in 1:70M:

[![enter image description here][1]][1]

[![enter image description here][2]][2]

And when I go further to 1:35M the map is like I expect:

[![enter image description here][3]][3]

[![enter image description here][4]][4]


Is that the correct behaviour? Am I doing something wrong? 

  [1]: https://i.sstatic.net/yfc3c.png
  [2]: https://i.sstatic.net/nsD9e.png
  [3]: https://i.sstatic.net/58ISO.png
  [4]: https://i.sstatic.net/q2Pva.png