Fourth of July, Canada Day (even formerly called Dominion day), and American/Canadian thanksgiving are on my list of questionable holidays due to their charged relationship with the genocide and land theft of Indigenous Americans.
Even in 2019, the American Thanksgiving had a number of racist mainstream media portrayals in which white / non-native people dressed up as indigenous people for comedy skits, including but not limited to on SNL and on Youtube channels like Smosh. We seem to know that people shouldn’t dress up as other races or religions on Halloween, and yet it still happens by professional comedians in November
In fairness, Canada Day is a celebration of the union of the colonies, July 4th is a celebration of independence from GB.
Associating these events to other historical events is yikes… I imagine a lot of older traditions also have external reasons to point to in disapproval, but up through the late medieval period, when a civilization was invaded, it often just got burned to the ground, eliminated from existence.