>There's hardly any technical reason to choose Java in favour of Scala3 today, except one: the team's lack of Functional Programming expertise.
I disagree about your premise at multiple points, but I want to focus on just one point - In my experience, Functional Programming is a large enough of a technical reason to not choose Scala in a company of a reasonable size. It's actually such a big reason that it deserves more than as an afterthought as you have it written.
I worked in Scala for 10 years. Not only was it difficult finding seasoned Scala devs, but also we often had to compromise by hiring Java devs and training them on Scala. Time and time again, functional programming was always the most difficult hump for them to grasp and it took experienced devs forever to learn the language and a new paradigm at the same time. Sure, you could hire someone who knew functional programming already and came from a background writing Haskell, but they were rare and usually commanded exorbitant salaries that made sure they were never in the equation to begin with.
Not to mention, you better have a disciplined team with strict linting rules and styleguides, otherwise your devs will go off the rails using Scala in ways that the team isn't prepared to learn. Or if you have Java-trained-Scala devs, they might revert to their old OOP ways.
Because of that, it actually causes more problems, resulting in worse quality software and worse deliveries overall.
It's too much of a risk, really. Especially when Java is not really a terrible choice in a large enough organization - same huge JVM ecosystem, large pool of devs, mature toolset, etc..