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The number behind "FORCED" is your forced collapse threshold. If your disk matter reaches that number, your black hole automatically collapses.
During your run, your Threshold will increase together with the Mass of your black hole, but you will hit a point where it feels like it does not scale fast enough.
You will want to increase your Overcharge Tolerance in your BH upgrade tab. This will give you a bit more headroom before you are forced to collapse.
You can also upgrade Overcharge Safety Margin inside your Curvature Upgrades under Collapse Engineering.
It basically does the same thing, just persistently over runs.
The most important and most overlooked fact is: Forced Collapse Threshold Scales With Total Collapses!
When you start the game, you might have a Threshold in the couple thousands, but the more you Collapse, the more your Threshold scales with your Mass.
For example, after reaching around 200 Collapses, you will easily start your run in the Millions for your Threshold and will have no problems hitting Billions later down the line.
In case you're curious, you can find your Total Collapses in the Stats tab inside the Settings.
Increasing your Forced Threshold by collapsing a bunch also increases your normal Collapse Threshold, making it even harder to Collapse Quickly.
If you are going for Achievements, I strongly recommend you get the "Watch me dance" Achievement before pushing your Total Collapses, because it will make getting the achievement increasingly harder.
The same goes for the "Are you sure?" Achievement, although that one is a lot easier.