When I launch 1.16.1 and play for a while, my system starts having memory issues. When I check, the launcher, which is still running in the background has started consuming all available memory and often causes my system to thrash if I don't catch it in time and kill the launcher process.
This is on Linux (Ubuntu 18.04) and has happened for the two versions of the launcher i have used. the prior version (updated to make sure it wasn't already fixed) I had been using with 1.15 I believe since it came out. It did not happen before I started playing on servers running 1.16.