Remove white space from Density Plot

Well I looked into your Data and I get nothing strange to what data points are:

data=tablogdiffxsec;
plot = ListDensityPlot[data, PlotRange -> All, 
       PlotLegends -> BarLegend[Automatic, 
       LabelStyle -> {FontWeight -> Bold, FontSize -> 11}],  BaseStyle -> {FontWeight -> Bold, FontSize -> 13}, 
       ColorFunction -> ColorData["CMYKColors"]]

Lets, Just select some points within the small reddish region:

Select[data, First[data][[1]] < #[[1]] < 1.15 && 0 < #[[2]] < 50 &][[1 ;; 10]]
(*{{1.1437, 0.18, -13.466}, {1.1437, 0.36, -13.4667}, {1.1437, 
  0.54, -13.4678}, {1.1437, 0.72, -13.4694}, {1.1437, 
  0.9, -13.4714}, {1.1437, 1.08, -13.4739}, {1.1437, 
  1.26, -13.4769}, {1.1437, 1.44, -13.4803}, {1.1437, 
  1.62, -13.4842}, {1.1437, 1.8, -13.4885}}*)

and, yellow/blackish region,

Select[data, 1.18 < #[[1]] < 1.20 && 0 < #[[2]] < 50 &][[1 ;; 10]]
(*{{1.185, 0.18, -3.16836}, {1.185, 0.36, -3.16845}, {1.185, 
0.54, -3.16861}, {1.185, 0.72, -3.16882}, {1.185, 
0.9, -3.16909}, {1.185, 1.08, -3.16943}, {1.185, 
1.26, -3.16983}, {1.185, 1.44, -3.17028}, {1.185, 
1.62, -3.1708}, {1.185, 1.8, -3.17138}}*)

Plot is conistant with the points.

Update:

You can set the option ClippingStyle -> Automatic, in which case the region that was clipped by PlotRange -> Automatic will be filled in with the surrounding color, ie. blue.

Note that this means the legend isn't completely accurate then, since it doesn't have a good way of indicating that the bottom blue color is really an extended range of values.

In V12.2 on my system, I get a different choice for the automatic plot range calculation, resulting in a smaller area that got clipped:

Here's an example where I've approximated the plot range shown in your screenshots: