I'm struggling to find its name online. It's a line chart but each point of the two series are joined, as the combination of both of them is what defines each datum:
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It looks to me as a Range chart or Area Range chart, as what defines the main data is the range between the maximum and minimum value and not the values independently.
As seen here https://www.highcharts.com/demo/arearange
Range plots are a relatively new* chart type. It's an extension of the dot plot, which William Cleveland created in the 1990s. Dot plots show one or multiple dots on one line. Range plots show exactly two dots on a line and connect them with an extra bold line.
*Aug 10, 2018
How to create a range plot - Datawrapper Academy
I think this is a classic Candlestick chart, in which there are three data related per period.
No doubt, it’s a line chart, you can design this diagram in the following manner as well :