Rows with logs should have their background set like:
dark
light
dark
light
...

But in some cases using filtering this pattern breaks. It seems the background color is set when page loads, before the decision, which rows will be displayed is made. When there are logs with different log level, e.g:

INFO
WARN
INFO

and their backgrounds are:

dark
light
dark

then if the filter is set to show only INFO logs, table will change to:

INFO
INFO

with background colors:

dark
dark

Using the same principle it happens that the table starts once with dark row, other time with light one depending whether omitted log is the first one in the table or not