Ouch.
Did these injuries happen decades (60s-70s) ago with the same frequency?
I don't recall it but perhaps we now do with social media.
Most of these tears happen using heavy weight but not all.
I think, without seeing any data, that most bicep tears occur outsiide the gym. Moving stuff, falling and catching yourself. This one hasn't been linked to steroid use as strongly as pec tears, not to say steroids can't make it mire likely. I read one paper 20 years ago about bicep tears and I can't remember any mention of steroids. The average age when tearing it was 36 years, fwiw lol.
As oldtimer said, it should be operated on quickly. However it can sometimes be operated on successfully even after many weeks. This happened to me last year. Accident at work, then like 3 months waiting around for surgery. Thanks to socialised medicine here. They tried to discourage surgery but I insisted, said it was life or death for me lol. You can recover most strength even without surgery a lot of times but I don't want that shriveled up Dorian arm.
Orthopedic doctors said STEROIDS! the first thing when they saw me. "This is what happens!" They warned me that if they let me have surgery I could not take any steroids afterwards.
The biceps is still attached and I did use steroids the whole time after surgery. They can probably hurt recovery in some situations but I didn't care enough. There is an uncomfortable sensation in the tendon sometimes, lost a little superficial feeling in my forearm but that has resolved a lot as nerves grow back. The surgeon told me that 16 weeks after surgery you should stress it with max weights. "I'm being careful when lifting doc." "No, you should lift as much as possible without jerking the weight, the goal is complete recovery to previous strength levels."
I had deadlifted at least 300kg most weeks for like 12 years straight, with a mixed grip. Like someone said, it's important to keep the supinated arm completely straight throughout the movement. A lot of times you see deadlifters, especially the less experienced ones, bending the arm ever so slightly when lifting. You should try to get away from this natural tendency by being concious of it until it becomes natural without thinking. If you want to be as safe as possible.