I had the same thing happen last year. Berkely Big Game... Not good stuff... I don't know if its the line in your case, but it was the problem in mine.

Check your line when its broken. Does it look like a clean cut? Probably the line itself snapping. Mono gets stretched out slinging those big baits, and eventually weakens and breaks.

Is it all jagged with little nicks above it? Probably got sawed off. Get a heavier trace leader like a foot of 30 pound so the teeth don't slice it as easily.

Is it kind kinded and swirly? Probably the knot slipped.

Line is weird stuff. Try playing a round with some brands and seeing what works. I use 20 lb Sunline Shooter and love the stuff!
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Go big or go home!