I can confirm it's due to the DRIP, and not because of BMO IL.
https://www.vanguard.ca/en/investor/products/products-group/etfs/VCNThe last VCN payment date was January 9, 2023.
My VCN in non-registered, and NOT set up for DRIP. January 9 Dividend paid out cash on January 9.
My VCN in TFSA, set up for DRIP, Reinvestment at $40.06 unit price on January 13, showing Dividend on January 9. But both only showing in transaction history after January 13.
I called my broker a few years ago, when DRIP happened not till the 16th or so, making me nervous. They explained it as needing to wait to know what the DRIP unit price was. Vanguard confirms it:
https://www.vanguard.ca/en/investor/products/resources-group/dripOnce you've enrolled, your distributions will automatically be reinvested into units purchased on the open market in the five business days following the distribution payment date. You'll receive your new units on or about the sixth business day after the applicable distribution date.
The price of your new units will be the average price of all units purchased under the plan excluding commissions, fees and transaction costs incurred by the plan agent. Fractional units won't be purchased, but rather paid back into your account as cash.