Increase virtual memory on your computer (if possible, some organisations won't allow you to do this, you will have to go through a system administrator within your organisation).
Here is a link with instructions on how to do it.
I would recommend a different approach that should work a lot better. To start off with, I would not use QGIS 3.10.12 anymore. Please upgrade to 3.16 or 3.18 and you will notice significant improvements in processing.
Load the point data into QGIS.
Create a raster from the point dataset. You can try the following tools: Rasterize (vector to raster) or any ...
I've tried quite a lot of different approaches to process the underlying DEM so that the generated contours don't contain spurious sinks. The approaches involved a mix of filters, and warping the DEM to double the resolution.
Of all of the approaches, there were two that gave reasonable results, so I'll post them for the benefit of others grappling with the ...