Thanks for sharing your report with us, @KalleKala82. I'm sorry to hear that you've encountered trouble with fire damage in-game.
The "leap" you're describing sounds very similar to a teleporting issue that has been reported to the development team. As the name suggests, Eivor will "teleport" a short distance away suddenly, usually in the direction being travelled. Generally, you should be able to continue moving as normal after the teleport. The team are investigating this issue further, and any future updates regarding this teleporting issue will be shared within the News & Announcements forum.
Were you able to capture a video which demonstrated what exactly happened when Eivor died near-instantly to flames? A video that demonstrates the incident happening in-game would be helpful for reproducing the issue in further investigation.
If this happens again, please can you capture a video and share it within this thread? I recommend uploading any videos to a sharing platform, such as YouTube or Google Drive, as this will allow you to post a shareable link within this thread. We can then pass this video along to the development team for a closer look.
Thanks!