Thanks for your report. I've tried to reproduce the issue on testing and I can confirm it; I've then looked in the upstream bugtracker and found that a similar issue had already been reported:
https://gitlab.com/pdftools/pdfposter/issues/2 The reporter has worked about the issue by using pdftops and poster. I'll try to understand better what's happening, but with little hopes, since upstream apparently hasn't solved it yet. I've removed the newcomer tag because the easy part was just reporting upstream, investigating the issue doesn't look like "This bug has a known solution but the maintainer requests someone else implement it. This is an ideal task for new contributors who wish to get involved in Debian, or who wish to improve their skills." ( https://www.debian.org/Bugs/Developer#tags ) -- Elena ``of Valhalla''
