Definitely not only because of bidding low manually. If you’re using automation, say target CPA, then if the searcher doesn’t look like someone who will convert then google will automatically bid lower = higher loss by rank, just not the same way as approaching it like ‘I need to bid harder’.
A high loss by rank could demonstrate the conversion you’re optimising to is too far down the funnel, or the target audience is very narrow.
Missed context from your previous post, but want to make sure you’re considering this aspect.