Grids of basemap when exporting PDF in QGIS print layout

Question

I've been getting perpendicular lines through my basemap imagery in my QGIS layout exports to PDF (see photo).

Some notes:

• The lines do not appear on the export screen.
• I have guides built into the layout, but they are not aligned with the lines.
• They appear across different imagery sources both WMS and downloaded .TIFF and .JPEG raster files.
• They do not appear when I export the composer as an image.
• They are not unique to the print layout, when I create another layout from scratch they still show up.
• They do not appear in my colleagues' exports using the same .qgis template files.
• The lines do not go through the shapes which make up the frame surrounding the basemap.
• The lines are in the same spot every time, towards the bottom and right.

I haven't been able to find anyone else with this issue on line.

My QGIS version is 3.20.3 and I'm on Windows 10 Home, 10.0.19043 Build 19043

Answer 1

In layout view go to 'Layout' tap > 'Export Settings' and check 'Always export as vectors' Had same problem at that moment ;-)

Answer 2

You can remove the grid lines if you disable the tiled raster layer export in the PDF Export Options:

BTW: it would be cool if QGIS Server will support this feature one day (https://github.com/qgis/QGIS/issues/51238).