Etsy's dashboard is not real time.
Views and visits in particular can be hours behind.
And at points in time, views from bots are filtered out. So 400 views could turn into a lower number a few hours or a day later.
And if you mean that you had 400+ views on Monday, but have fewer today ... well that's fluctuation. It's normal.
Orders and revenue are pretty reliable but I've seen even those disappear around midnight and get reset correctly the following day.
I admit that I look at my dashboard often, even though I know that it's usefulness is very limited.
If you like data, the stats page is better source, using longer windows - last 7 days, this month, this year, etc.
