It feels a bit disrespectful that he thinks he needs do dumb down anything he says to me.
If I were talking to someone experienced in that way, I'd surely be behaving in a passive-aggresive way. I wonder if he's extremely annoyed at me and this is his way to show it.
But consider, maybe he explains things like he does regardless of who he is talking to? Sometimes the best explanation for a junior developer is also the best explanation for a senior developer. Do you have any other reasons to believe he disrespects you?
You probably want to tell your boss "stop disrespecting me and giving me junior level explanations, stop being patronizing". Of course, you can't just say this... or can you? You can probably find a way to say this if you "grease it" with enough respect. Find a way to be honest and respectful. Maybe something like "I appreciate your explanation, but I'm having a hard time following. I think it would help if we could talk about things in higher-level terms I'm already familiar with, I already know what an API is so we can just talk about API's without going into more detail, the extra detail is distracting me from the thing I want an answer about, etc."
Just trying to give some advice that might help if you want to stay. But again, leaving might be the right choice too. Your call. It would help if you would be a little more concrete about what and how he speaks.
I think this might be key. If he talks to everyone, or most people, this way then you should be able to make it less personal.
Regardless, it might be good to start doing 1:1's with your manager. I get the impression that this isn't something that is part of your company culture? But doing a fortnightly 30 minute session where you talk about "stuff" (not specifically work stuff) can help build a relationship between the two of you.
You say you're in the business for 20 or so years, when you interview for a new role have you ever had the question asked along the lines of: Have you ever encountered a difficult problem at work and how did you solve that problem?
Well, here it is. Rather than leaving, try to solve this problem. It will be difficult and you will have to get out of your comfort zone. But I think you might want to look at this as a growth opportunity instead.
Good luck!
Your boss should be a better gauge of your skill level and adjust his language accordingly.
On the other hand it's on you to tell him that the level he is communicating at isn't right for you and he can skip the explanatory stuff if he's doing it for you.
I would be THRILLED to have someone who wanted to explain things like I was 5, lots of people don't
Can you give an example?
One of my biggest annoyances with devs is that they rarely give "upward feedback". They expect their manager to just magically know how to manage them, and they complain if their boss gets it wrong. You can just tell people though - say "I'd like to give you some feedback that will help us work better together..." and explain what it is that you find annoying. If your boss isn't a dick they'll take this onboard and change.
Everyone should learn to give better feedback. It's one of the things that separates a mediocre team from an awesome one - people actually trying to work together better.
Yes that's a big if. Also, every personal conflict cannot be solve just by talking... Sometimes, you have genuine differences in goals and optimal behavior. You don't need to be a dick to treat people poorly. It's just need to be in your best interest.
Great in theory. Bad in practice. upward feedback is really a hit and miss type of situation. The brunt of the rest is toward the dev in this case. Not much upside and a lot of downsides.
Please consider having fun with it or getting promoted over him.
Now you're learning why.
If your boss wants to be king of a shithole with his behaviour, he will be the only person in the company or the company will fire him.
Life is too short to deal with people who are disrespectful to your expertise and think they either know better than you, condescending, manipulative or are passive aggressive.
If you leave the company and tell others how bad the boss is, they might follow you in leaving as well.
I have the same advice, but coming from a slightly different perspective.
You haven't given us enough information to actually judge accurately the situation :
Maybe you are below the expectations for you level, maybe you are asking questions which you should already have the answer... And on the other hand, maybe your boss is just an inconsiderate a*hole, have some weird age related prejudice, or just an immature person.
Or maybe you both just have two very different communication styles, "He will explain like I'm either very junior or a 5-year old." might just be the way he explains things to everyone and you are taking too personally.
I have seen both sides, and countless of in between. But at the end of the day it always ends in the same place. Perceptions are hard to change, and people get very defensive when confronted with their mistakes.
At best, you have a "hard conversion" with your boss, the problem is resolve. And you get a "normal" work environment. At worst, the hard conversation goes south : your boss pretend to treat you differently, but deep down now see you as an under-performing and now complaining employee. Do you really want someone like this decide your promotion/compensation packages ?
There is a lot of talk about "hard conversation", navigating difficult personalities etc... etc... In my experience, that works well between peers of equal standing. Between employee/employer , the power differential make this a moot strategy.
Or maybe you say nothing, and work extra hard to prove yourself. But then you are working harder to go from -100 to 0...then get burned out in 6 months. Why not just apply the same effort somewhere else and go from 0 to 100 ?
Obviously you want to do your home work. (self-)reflect on your behavior and take your part of the responsibility in the equation. If you have someone you trust at work, getting another perspective is really valuable. where ever the fault lies, you can still learn from the experience and grow.
I like the (medical) saying "don't order a test if it doesn't change the best plan of action". IMO, the environment you describe if not really conducive to sustainable long term success. The job market is very hard right now, so it might still be your best option. But if you can... slowly start exploring external options.