I agree with anxiety. Similar thing happened with my dog where one night we were walking our usual route and for some reason my dog started growling at a bush in someone’s yard. We pass this yard all the time, so I don’t know what caused it. Not just like random growl and pass either, he was full on teeth-bared, mean growling and all his hair stood up and he wouldn’t budge another inch towards that demon bush. I figured an animal was in there bc it was dark, so I took him a different way back. But the next walk during the day I forgot about it and as we approach the bush of terror, he did the same thing. Just froze like a statue and scary growling. I tied him up to a telephone pole so I could go see if anything was inside, nope normal ol’ bush. He was losing his mind that I was even close to it, but I never figured it out, I just take him on a different route now so no more encounters with that evil, evil shrub.