IanFrost, that's a great question!
So, if Safe Mode seems to not see the issue occur, let's go ahead and restart normally. Safe Mode automatically refreshes some system data, and it is possible this in itself will correct the issue. If not, we now know that it is something happening at startup, allowing us to narrow down possibilities by reviewing your account's Login Items.
To check, go ahead and click on > System Preferences... > Users & Groups > your login > Login Items. In the box, we'll see all the apps that run when your MacBook Pro starts. We'll go ahead and remove them one at a time, restarting between each one, until the issue goes away. When it does, we'll know whatever was last removed was the cause.
Hope that helps!