I am also having this problem. Yes, it is extremely annoying.
In R2019a it appears to be somehow connected to the menu bar, and if I disable the menu bar, it suppresses the behavior.
This exhibits the problem:
f = figure;
This does not exhibit the problem:
f = figure('MenuBar', 'none');
Most of the time I can live without the menu bar, so this is an acceptable workaround.