Hello, I'm using a document management system (SeedDMS for those who know) through Firefox 122.0.1 (64-bit, canonical 1.0, downloaded from packages.ubuntu.com for focal, running on Debian Bookworm, kernel 6.1.0-17-amd64/Debian 6.1.69-1 x86_64, X.Org X Server 1.21.1.7, KDE Plasma 5.27.5, KDE Framework 5.103.0, QT 5.15.8, i7-5820K, GeForce GTX 1070). Within this document management system pdf.js (v4.0.379) is being used to preview/view PDF Documents. After starting Firefox the PDF view inside the DMS works fine until I suspend (to memory) and resume my machine. Regular HTML-content looks fine but the resumed DMS session shows only blank (all white) Pages inside the PDF view. Changing to a different PDF file doesn't help. The number and size of these pages is presented correctly. I can even select and copy (invisible) text from these blank PDF pages. The problem applies to all PDFs, whether they're single or multi paged, have images inside them (like with PDFs from a scanner) or not, etc. Reloading the page/closing reopening the affected browser window doesn't help, i.e. the problem persists. I recently found out, that this also applies to PDF files directly opened inside Firefox (which also seems to use pdf.js as a PDF viewer), that is, this is not related to a specific site like my DMS. The problem always persists until I kill Firefox and start it over. Pdf.js seems to use a canvas inside a div (see screenshots attached) to draw the visual PDF content and another div to make the text layer selectable/searchable etc. I don't know what's happening to canvases on a system suspend/resume cycle in Firefox on Linux, but I suspect that's where the problem originates from. This problem already affected older versions of Firefox and pdf.js. Please let me know, if you need further information from my side to investigate that issue. Thanks a lot!