In the extension version I see the months with \Jan behind it: While in the web version, I don't see this problem:
Also the display of Worklog Report in the JA extension version and web version is not readable when containing multiple user groups:
Thank you @SSeltonrijch for reporting this issue. The first issue you reported about Month name wrongly displayed is already resolved and as you mentioned is available in Web version. Next time the extension is published, this issue would be resolved.
Second issue about dark theme in worklog report is resolved and is now available for Web version. Soon after extension is publish, this would be resolved for extensions as well in JA v2.49.
Closing this ticket considering both the issues reported are resolved. Please feel free to reopen it if you still face any other issues.