Compare "From" and "To" are confusing
The naive interpretation of from and to on a compare view indicate that the diff you see should be what would be merged if you checked out 'to' and merged in the 'from'. The actual interpretation is "here is the diff if you checkout 'from', and are going to merge in 'to'".
I think gitlab should adopt github's renaming of those labels to 'Base' and 'Compare', they are at least less confusing.