When exporting charts to SVG viewBox parameters are huge. Thus when you generate PNG from this SVG the PNG is two orders of magnitude bigger then needed.
Steps to Reproduce:
1. Plot chart
2. Export chart to SVG
3. Open SVG in text editor
viewBox="0 0 47300 24900"
viewBox="0 0 473 249"
User Profile Reset: No
OpenGL enabled: Yes
Alex, please attach a file example and write here info from Help-About dialog
Created attachment 165979 [details]
Huge ViewBox in Calc Chart SVG export
Build ID: 1:6.4.6-0ubuntu0.20.04.1
CPU threads: 16; OS: Linux 5.4; UI render: default; VCL: gtk3;
Locale: en-US (en_US.UTF-8); UI-Language: en-US
Created attachment 165984 [details]
Normal viewBox generated by SciDevis
For comparison. SVG generated by SciDevis. viewBox="0 0 1801 901"
Alex, why did you close the bug report in the end?
It was not the problem of Libreoffice. Yes the viewbox was too high dps. But problem was in the other application. Specifically wrong (unsupported) keys in mediawiki default installation.