When LibreOffice has an uninstalled update available it shows an icon of a globe at the top right of the screen to indicate the update is available. When you click on this you are taken to the LibreOffice web site where you will (if you are trusting and innocent) download and install the full version of LibreOffice on the PC you happen to be sitting at.
This icon is visible whether you are running the portable or the original version.
If you are using the portable version because you want to leave no trace on the PC you are sitting at, then I suggest that installing the full version of LO might make mincemeat of your good intentions.
I have created a request on the LO Support page (Bug 162141) suggesting that the LibreOffice software should determine if the portable version was executing and not display the globe icon. but the only respondent so far suggests they ignore it as "not our bug".
Can you help?
https://portableapps.com/comment/253057#comment-253057
“All these years that I had spent in the service of mankind brought me nothing but insults and humiliation.”
― Nikola Tesla ―
“I'm such an open book, but you shall read between the lines.”
― Neo Buddha ―
In Writer go (menu) Tools > Options... >LibreOffice > Online Update. In the settings there just turn the option to "Check for updates automatically" to off.
Use Portable Apps on both Flash Drive and HDD/SSD.