Why does leaflet map not load if accordion is closed?

Question

OpenStreetMap

I am using Vuetify accordion and nuxt-leaflet package .
If the accordion is not opened immediately when loading the page, then the map will look like this:

Only a part is visible, and when navigating through other parts of the map, the layer does not load normally.
If, when loading the page, immediately open the step with the map, then the map is displayed normally:

Can someone explain why the loading of the map introduces itself like this? And how to fix it?
Added example https://jsfiddle.net/vodnicear/8a162res/5/