Google is canonicalizing Canadian site to US site and vice versa (despite set canonical ta

So my client has 2 sites, one for Canadian customers and one for US customers, but both are .com domains. According to Google Search Console's indexing report on each domain property, hundreds of pages are flagged as duplicates and Google is cross canonicalizing pages: the canada version to the US version and the US version to the canada version. This is happening despite the fact that these pages have self-referencing canonical tags.

Am I right in assuming this is because the sites are both .com sites, and that the Canada site should be .ca? If so, should my client switch their .com Canada domain to a .ca domain?