> Especially historically it was pretty hard to get the JVM to release memory back to the OS.

This feels like a huge understatement. I still have some PTSD around when I did Java professionally between like 2005 and 2014.

The early part of that was particularly horrible.

This only really ends up being a problem on windows. On systems with proper virtual memory setups, the cost of unused memory is very low (since the the OS can just page it out)

Java has a quite strict max heap setting, it's very uncommon to let it allocate up to 25% of the system memory (the default). It won't grow past that point, though.

Baring bugs/native leaks - Java has a very predictable memory allocation.