Hot break is coagulated protein material that clumps together and drops out of suspension during a vigorous boil, visible as flaky, sometimes foamy material forming on the wort's surface roughly 10-20 minutes into a rolling boil — a normal, genuinely desirable part of a healthy boil rather than anything to skim off or worry about.
Why a weak, gentle boil produces a weaker hot break
Hot break formation depends on a genuinely vigorous, rolling boil, not just wort sitting at a bare simmer for the same length of time — a boil that's too gentle produces less complete protein coagulation, leaving more haze-forming protein material in the finished wort than a properly rolling boil would remove. This is one of several reasons "boil vigorously" shows up as standard homebrewing advice rather than "keep it warm for 60 minutes."
Hot break and cold break are two different, sequential events
Hot break happens during the boil itself; cold break is a separate, later precipitation of additional protein and polyphenol material as the wort rapidly cools afterward — both contribute to the trub layer settling at the bottom of the kettle or fermenter, and both are working in the brewer's favor toward a clearer finished beer, not against it.