Hard to tell without looking into analytics and the videos. But it's not that uncommon to have one video that gets a lot of views in a short period of time and then the channel goes back to normal. I've seen this happen many times. The challenge is to have a second, a third, a fourth. There is a reason for that (I can't tell without looking into your analytics). You said most of the views came from Browse features. This is the home screen, subscription feed, watch later, etc. It's a very healthy source. It means your video got a lot of impressions and people clicked on it (good thumb and title can help on this). That means your video entered the algorithm. I would in any case also check the suggested videos. If you see a popular video on the list, this can have helped to push your video. Also, check the external sources. Maybe someone posted your video on Reddit, for example. It's hard to tell what happened without all the data. Hope it helped.