Even when I vacationed in Bayern (Bavaria), a lot of people switched to English when they realized that my German wasn't that good. Which was frustrating, because I wanted to practice speaking with native speakers.

Although, there were also people who only spoke German.

If you want to learn you just pretend that you don’t speak English and keep on speaking German. They will switch back fast.

This is the right way. Speak the language you want. Even if they reply to you in English, and they know you can speak English, continue in German. They will understand. They switch to English because they want to be helpful. If you continue in German they understand you prefer it that way.

Another thing is that once you start talking with a person (who you meet on a regular basis) in one language, it is hard to switch to another language at a later date. So if you start with English, it is hard to go back to German. But if you start with German, even if it is less fluent for you, it will come natural that with that person you speak in German.

Did you ask if you can move to a different city and work remotely? Even if only 1-2 years, it might really help to boost your German. Moving to Dresden, Hanover, or Hamburg would help. (German HNers can probably recommend a bunch of small cities 1-2 hours away by train/car from Berlin that will use much more German language!) You could come to the office once a week.

Another tip: Always start the conversation in German. If the person switches to English, ask them politely to speak German, and explain that you are studying German. My parents did similar when they moved to the Netherlands 50 years ago. The local shopkeepers were eager to practice English with my parents, but my parents were also eager to practice their Dutch.

That's really good advice, but I found it hard to put into practice because my German was so bad. And German isn't a language you can just hammer out a badly-formed sentence in; word position is less important than conjugation, so if you get the conjugation wrong it makes no sense at all to the listener. I did try this a few times, but everyone lost patience with the painful butchering of their language when they realised their English was a lot better than my German.

I would have moved city, but a: COVID b: my wife also had a job there c: I really loved Berlin and really enjoyed living there

I like the effort! It is more that half of the battle when learning a new language as an adult. What really helped me: Create your own custom Anki deck. Literally, start from zero. Each time you try-and-fail (or think of something that you don't know how to say), write a note to yourself in English/broken German with the sentence/idea that failed. At home, use a translate tool (LLM/Google/whatever) to build the correct German sentence. Next, add it to your Anki deck. Personally, I only add full sentences, never just vocab, because it adds more natural context. Only add real stuff that you will use. On the first day, you have an Anki deck with one card. If you are really motivated, try to add one card per day, but just 1-2 cards per week will quickly improve the deck. Since the deck is so damn small, you can blow through it in five minutes while riding the S-Bahn/U-Bahn trains. And, every single sentence is useful to you. Bonus: Ask a native German speaker about some of your Anki deck sentences. They will probably love to talk to you about the German language because you will be showing your commitment.

>everyone under the age of 50 speaks good English and switched to that as soon as my first badly-conjugated sentence left my mouth.

OK maybe things have changed in recent years. I was always annoyed when coming to visit family living in Berlin for a couple days or driving in to a conference, and inevitably there would come a time when I would have to ask someone for help and I would have to ask in English because I do not speak German (although due to youthful immersion I start to remember it again after a couple of weeks) and they would inevitably answer in German.

I could somewhat understand when we stopped in a park asking where the convention center was of just a couple people by the side of the road, but asking a ticket agent at a train station what route I should take to get to a particular station and getting replies in German seemed especially rude.

At any rate despite some good experiences with Germans regarding helpfulness I have had a few too many negative experiences.

Berliners are renowned even in Germany for being blunt to the point of rudeness.

What we in the Anglosphere would consider rude, they consider efficient. It can be very off-putting at first, but you do get used to it.

in most other countries renowned for being efficient it would not be considered efficient to answer in a language the questioner evidently does not speak.

To play the devils advocate: It is efficient — for them.

It is a bit of a myth that everybody in Germany talks English. Sure in an academic or business environment, or in certain social circles that can be taken for granted, but there are people who can only talk German or whose English is so bad they will avoid talking it.