Keep in mind in Canada the sun contributes to natural vitamin D production in humans from May until September. Vitamin D likely reduces cases and severity of covid, so like last year when the natural vitamin D began to decline in September cases began to increase. This time around the skyrocketing cases will make it look like vaccines are largely useless and it will be difficult for Trudeau to argue his (failed) vaccine strategy saved Canadians. So yeah having an election before the end of September makes sense from a Liberal perspective.