I thing the size of first opened terminal window is the same as configuration window. Can you for first window (first tab) resize window instead of using the size of configuration window. I use 14 pt font and 69x24 is very low and need to be resized for any use of terminal. Issue is not critical but can reduce the number of "resize on open" for first opened terminal window.
Open putty-nd, set the windows size 80х24 and check "Change the number of rows and columns" for connection, save settings, open connection. Connection open with window 69x24 instead of 80x24.
Initial window size differ from saved settings