Reactivity amping up with age?

Hi all! We’ve had our puppy for nearly three months now and he’s going to be five months old in a few weeks. The time is flying and he’s honestly been doing really well with most things. He is crate trained, does well with commands, has stopped chewing on things he shouldn’t, and rarely has accidents in the house (just the occasional excited pee when someone comes home). We’re still working on side-by-side leash training and reinforcing commands outside with distractions.

The one thing I have noticed over the last few weeks: the boy is starting to bark at things he’s never barked at before. He used to just watch as other dogs walked by but now he barks at them – especially if they’re across the street or down the block. He barks at people now too – again mostly if they’re a little further away and mostly if it’s dark out. He’s also started barking at home (we live in a multi unit building) – mostly if someone is stomping down the hallway and making a lot of noise. For the outdoors, we’re doing our best to try to redirect him/have him sit and look at us while continuously giving treats and talking to him.

The only other change is that he goes to daycare a few times a week now as I still don’t trust him to stay home alone. We don’t have the best space to keep him gated (the boy is 22lbs already and can climb). I don’t want to leave him in the crate all day with only a few drop-ins from a sitter especially with how energy he has.

I guess my main question is: is this normal as pups get older? Or does this happen to dogs as a result of daycare for some reason? I feel like we’re doing things mostly the right way but I’m just concerned with the change in his behavior. Any insight or help is appreciated – TIA!!!