What is this bug
This is a praying mantis, a beneficial insect. They usually hibernate over the winter, but your garage (and a diet of stinkbugs) must be keeping him around. As it gets colder, he will either hibernate or die. If we have a fairly warm day, you could try moving him outside to a sheltered sunny area, where he may be able to find a place to overwinter safely.
Here's more fun info: https://extension.umd.edu/hgic/topics/predators-praying-mantid-mantis
Sorry. Meant to say they overwinter as eggs in an egg case. This guy is going to die one way or the other before spring. He will not make it through the winter.
Thanks for the info.