Seriously? This is an old wives' tale, or at least a highly overblown concern. For someone like you, focused on gym gains and consistent nutrition, canned tomatoes are a solid, nutrient-dense choice. The cooking process involved in canning actually makes the lycopene—a powerful antioxidant—more bioavailable than in fresh raw tomatoes. So, in that specific regard, they can actually be *better* for you.
The 'weird' thing you heard probably relates to BPA (Bisphenol A) in can linings. This is a legitimate concern, but easily mitigated. Simply opt for brands that explicitly state they use BPA-free cans, or go for tomatoes packaged in glass jars (like passata or whole peeled). Don't let fear-mongering distract you from practical, effective nutrition. Keep your focus on hitting your macros and progressive overload in the gym. This is a non-issue if you choose wisely.