This might be a bugged fix of
When you select some text in the Game Output and enter new commands, the Game Output will stay at the same position but you will notice that the scroll bar on the right side changes.
When you now mark some text and create a fill or setblock clock, you will see that after some seconds the marked text isn't in the Game Output anymore. Now stop the clock and scroll to the end of the Game Output and enter a new command. You will see that it still jumps to the first position. Only when you mark something new it will go there (so it will never automatically go to the end anymore). This might be also caused by the fix that the Game Output showed the complete log which caused it to nearly freeze or to show characters incorrectly.