It happened in our last 3 elections in Canada and down south in the US as well.
The leftists lead by a wide margin for the whole month, but then the polls shift right at the end for no reason.
Don't you remember how far ahead Hillary was for that whole last month? She had "a 95% chance of winning" for most of it, then 85%, then right at the end the polls were suddenly down to within a couple percent the day before the elction.
It's always that way in Canada, and the US. Big lead for 29 days, small lead for the last day and a half.