Lifting heavy weights

I heard that it might be harmful to your arm if you lift weights to become “buff”

Like heavy weightlifting 3 times a week or something like that
at the gym

But I also play football so I do heavy weightlifting in the football season.

Advice?

Heavy weights have nothing to do with hypertrophy, the increase in muscle size (but not necessarily strength). Bodybuilders don’t lift heavy, they lift lighter weights for more reps.

Look up Joe DeFranco’s WS4SB article. He explains how to mix heavy lifting with other aspects.