See what you can get by putting some subtle feelers out. Talk to a recruiter or two. Best time to search for a job is while you have one, but you don’t have to commit to it full time unless shit really hits the fan. You’re more likely to get written up than fired initially anyway if he’s not the owner, erratic or not he has to answer for that.
Continue working towards whatever certifications you want in the meantime, especially if the job pays/reimburses you for it.
Idk if that’s out of control or not anymore, what’s a dollar worth? But I’ve avoided goodwill for Habitat for a while because there were various stories over the years about shady things. Now, they’re big and basically all franchises so some of this was always gonna happen; lawsuits w/ racist/sexist/otherwise discriminatory managers will eventually happen once a company gets large enough, and franchises have a lot of independent control which leads to a lot of variance, good and bad, at different locations.
But they’re also pretty shit at the corporate level: https://www.cracked.com/article_33357_15-impressively-evil-things-goodwill-has-done.html
So overall, on the astronomically low bar of regular evil corporate behavior, they’re middling, but you should probably donate/shop elsewhere if you want to do the most good.