The latest version of Vivaldi includes some security fixes from a newer version of the Chromium browser engine, so this is an important update.
Other changes in Vivaldi 1.13.1008.40 are almost all regressions, meaning that they are fixes for things that were previously fixed but broke again in recent updates. The frequency of these regression issues in Vivaldi is troubling, as it seems to indicate some sloppiness in the development process.
The announcement for Vivaldi 1.13.1008.40 makes no mention of the new version number, and fails to link to anything like a change log. It’s unclear whether these omissions were intentional, or just mistakes.