Open plugin manager, installed plugins.

Type a filter text like "file" into the filter field -> The installed plugins are filtered.

Click the "X" button on the right of the filter box.

Bug: The plugin list remains filtered. The filter field text is empty, but the filter remains active until some key is pressed inside the filter field. Screenshot shows the situation, the filter "file" is still applied and only 4 plugins are shown, even though the filter field is empty: