I've checked these sources:
https://www.cbc.ca/news/politics/grenier-sloan-independent-1.5882603
and I haven't seen any other issues being raised. There was mention that he accused Dr. Tam of siding with China and the WHO, but that doesn't seem like a racism issue so much as an issue with the objective fact that China has lied about Covid and the WHO has repeated those before (knowingly or unknowingly).
Every article claims he has said some controversial things, but the fact that they don't even quote them or have screenshots of tweets tells me they're probably not even offensive. If you have something you could share with me I will definitely take a look!