While I was writing a topic about the problem I observed after the today (18/July/2023) package.
I selected few lines of the output to added to the topic and instead of copy only the selected lines, the IDE copied ALL output lines.
How to check:
if the select lines was on the same screen page, it works; but
Please provide detailed instructions I can follow to reproduce the fault. I just did some experimentation and was not able to reproduce it so far, but that might be due to a misunderstanding of your report.
When you say "the output", are you referring to the contents of the "Output" view in the bottom panel of Arduino IDE: