Why exactly is this? Are there really that many non Germans speakers that you need to use English? And would you use English to have a chat at the water cooler, or down the pub (or locally relevant alternative).
I'm not OP, but also at a Berlin tech company. I always say I'm glad I learned German (in a much smaller city elsewhere in Germany) before moving here. You absolutely can learn German here, and I know people who have, but I also know people who've lived here for years and don't know enough to buy a loaf of bread in a bakery. The problem is that you can get away with it: your colleagues can all speak English (and some of them can't speak Germany, in some workplaces, including mine); as an expat, you probably live in a neighborhood with lots of other expats, where the staff in restaurants and shops speak English (and it's not uncommon for waiters to be unable to speak German); you can make your friends exclusively in expat communities, and if you arrive in Berlin speaking no German, that's a lot easier than integrating into the local community without yet knowing its language. It's especially bad if your accent gives away that English is your native language.
Watercooler talk is usually english unless I am around a group of people where I know that they all speak good german, but that rarely happens tbh. It's more likely to hear another group talking portuguese, spanish or arabic :)
It sucks, because it's harder to learn German, because you don't use it on daily basis. Myself including. But I find it ridiculous that some people after many years are not able to handle A1. Come on.