Mine is the lag in Stellaris, and lack of options to let me impact it. Like let me disable the ability for the AI to make habitats FFS!
I would take no progress bar at all. Progress bars are inaccurate because the time it takes for an action to be done on a computer is unpredictable.
It also causes an illusion of something loading faster.
Progress bars are bad indicators for representing remaining work or time, but it’s a decent indicator that something is still being done. Though it’s uncommon these days, I remember several instances of older games that has stopped loading. Showing the same percent for a minute is a decent indicator that something has gone wrong.
While I don’t care for percent as a displayed number, I do enjoy some kind of indicator showing that the loading is progressing.