OK, @mendy. So, the outputs of all the 3 commands that end in "| wc -l" (which counts the lines of the output) that you ran at my request are consistent among themselves, showing equal or very similar results. That is good! 
Regarding your other question:
That's probably the effect of the Bug #1922276 ("Select All (Shift+Ctrl+A) followed by Copy (Shift+Ctrl+C) copies only visible part of terminal output") that still affects Ubuntu MATE 22.04 LTS ("Jammy Jellyfish"):
https://bugs.launchpad.net/ubuntu/+source/vte2.91/+bug/1922276
@Norbert_X mentioned that Bug (and another one) in the following post, here in the "Ubuntu MATE Community" discussion forums, last year (in June 2022):
Other than that, I'm assuming that you've already (re)configured the "Default" Profile in "MATE Terminal" to change the default lines of "Scrollback" from the default of only showing the (last) 512 lines to "Unlimited" or, at least, to a large value. Right?