I noticed that the updates progress in Brave Nightly, as well as in the Beta version, behaves strangely sometimes. When starting Brave and checking whether an update is available, Brave initially loads for a while and downloads the update in the background (I know this due to network traffic from Activity Monitor).
After that, Brave states that no update is available, although reloading the browser tab eventually states that an update is available for installation. The user can then install the new update.
However, that is not always the case. Sometimes it states that even after a tab refresh no update is available. If Brave is then closed and reopened again, a new version of Brave has been automatically installed in the background. This behavior of Brave is only noticeable in Brave Nightly as well as Brave Beta. Brave Release Channel is not affected so far.
I have attached a short screen recording, starting where the update had already been downloaded in the background.
Current Brave Nightly version: 1.94.81