This is a regression from XF 1.5 and 2.0 too. Not certain it will be what you're expecting, but the key regression is that in XF1 we would trim a total of 1 line breaks from the end of the LIST tag. In XF2.1 we started trimming 2 for some reason. It seems to be deliberate but I think I agree it should be consistent. This may well resurface some edge case that required the change...
But rather than this:
We actually intend for it to look like this:
The <ul> tag itself comes with its own margin so to tighten it up we'd recommend not inserting your own line breaks before or after the opening or closing list tag.