Lately, when I try to download different files like .docx, .pptx, etc., Firefox always downloads files with a .pdf extension. I tried it in a different browser, and the problem does not occur there. Of course, the files are the same in binary terms, so when I change the extension, everything is fine, but it is annoying. What is wrong?

Firefox version 124.0.2-1 latest/stable OS: Ubuntu 23.10 Kernel: Linux 6.5.0-26-generic