If another Scottish independence referendum were held today, how would you vote?
Yes to an independent Scotland: 45%
No to an independent Scotland: 46%
Some of the insanely biased newspaper reports of this poll (which are probably lightly rewritten versions of a press release) suggest that with Don't Knows excluded, the figures are Yes 49%, No 51% - but there are no such numbers in the datasets. If this is simply based on a crude recalculation of the 45 and 46 figures, it may well be inaccurate due to rounding issues, because it comes out very close to Yes 49.5%, No 50.5%. In other words, until and unless we hear definitively from YouGov, it shouldn't be assumed that No are actually in the lead in this poll on the rounded figures excluding Don't Knows. It might be a 49/51 split, but it could just as easily be 50/50.
The drop in support for Yes since the last YouGov poll is therefore either one percentage point or two percentage points. It's not statistically significant either way. There are three possible explanations for the slight drop. It could just be random sampling variation (if Yes are on around 51%, you'd expect some polls to put them on 49% or 50% due to the margin of error). The unorthodox question sequence might have distorted the result. Or there could have been a real but modest slip in support for independence due to the 'Brexit lull' - ie. in some voters' minds, Brexit is 'done' and nothing disastrous seems to have happened, but in reality the cliff-edge is looming at the end of this year when the transitional period finishes.
As things stand, though, an average of all four polls this year continues to show a slight pro-independence majority.
Contrary to the impression you might have got from the press relea....sorry, original newspaper reporting, the poll actually detected considerable enthusiasm for a second independence referendum. 55% of respondents want it to take place within the next five years, and 40% want it by 2022.
UPDATE: It's far from clear whether 16 and 17 year olds were interviewed for this poll. The datasets for the last YouGov poll specified that over-16s were the base, but this time it just says "2587 Scottish adults". If by any chance 16 and 17 year olds were excluded, the media narrative about this poll would be completely bogus, because the Yes vote may well be underestimated by 1%.