The IMR plant has been operating in Quebec for many decades. They are owned by Hodgdon and all production is shipped in bulk containers to the US for bottling into retail packaging. My understanding is the importation regulations are different for retail packed powder versus bulk powder and since the US is the primary market, they want to keep the price down for US customers. It makes sense from an economic point of view. If they're selling 95% of it in the US, it's made in Canada, but they can make it cheaper for US customers if they package it in the US, then that's what they'll do. Then they can either charge less to be more competitive or, more likely, charge the same and increase profits.
The thing to remember is that Canada is an absolutely minuscule market compared to the US for anything firearm related. The US has 10x our population and 3x our gun ownership per capita. So we're looking at a ratio of 30:1 for US to Canadian potential customers.
Powder additives to reduce copper fouling have been used since at least the 1970's. The only one I've tried is CFE223 from Hodgdon and it noticeably reduces copper fouling but doesn't totally eliminate it. As far as I know the most common additive is tungsten powder which scrubs the barrel with each successive shot down the bore. The abrasive qualities of the powder are not supposed to significantly damage steels so they theoretically don't increase barrel erosion. Kind of like how a scotch brite pad for washing dishes will scrub off stuck on food but isn't abrasive enough to damage cookware or dishes. Since copper is significantly softer than steel this isn't that difficult.
I've seen the new IMR powders at one local store I frequent. They use much brighter colours for the labels compared to the usual muted tones from older IMR powders. I remember seeing neon green and neon orange I believe.
Another interesting thing about the IMR plant in Quebec is Hodgdon seems to have switched production of all the shotgun and pistol powders to the US side. There were rumours of several shipments being rejected after testing and finding they didn't meet the requirements/burn rates. Powders like 700x, 800x, and Trail Boss that used to be under the IMR label are now all under the Hodgdon label. They no longer say "made in Canada, packaged in the USA" but now say "made in the USA". The new rifle powders are still made in Canada so the rumours of them closing down the Quebec plant seem to be false. I guess they are just switching the IMR brand to only rifle powders (IMR does stand for Improved Military Rifle after all so I guess it makes sense).