This article will explain this in more detail than I ever could:
In cases like this you can install something like Timeshift, which is a tool to make snapshots of your system at a certain point in time. Later, you can rollback your configuration to a previous snapshot in case things go wrong.
For example, make a snapshot before updating or installing something. If after proceeding with that update you notice that something is wrong, you can rollback to the last snapshot where you didn't yet have that update installed and thus avoiding the problem. Like a checkpoint in a video game.
When it comes to boot and firmware updates... it's possible that even Timeshift isn't capable of giving you an easy way to solve this, since these updates are at a lower-level. But, it's worth giving it a try anyway.
As the article I linked to explains, this is a security fix. You don't have to apply it if you don't want to, if for some reason you need to be sure your computer works "as is" right now. For example if you have a presentation next week or whatever. Just hold on to this update until you're comfortable.