arduino 1.8.12 is out.
The recent port devel/arduino18 (incarnation 1.8.5) seems to have severer problems with a stable serial communication to some kind of ESP32 (using those ESP32 offered by AZ delivery in Germany).
BoardManager menu entry is missing in 1.8.5 as of devel/arduino18
Now up to 1.8.13; it is not trivial to update though.
Boards Manager has been patched out since this was added via PR213659
I came across this issue while following https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide/installing-mac--linux
The package should list these caveats on install