Sometimes Opera can get stuck in an update loop of sorts where an update installer keeps running and then Opera thinks it just updated, which might cause the splash screen to show every time.

While Opera is closed and while all Opera updater processes in the task manager are closed, deleting everything in "C:\Window\temp" and "C:\Users\yourusername\AppData\Local\temp". That might fix it.

If not, download the 105.0.4970.63 installer, goto the URL opera://about, take note of the "install" path, close Opera, uninstall Opera (do not choose to delete your data when asked), delete the install folder (it will be left behind with a few files in it), delete both of those temp folders again, launch the Opera installer, click "options", adjust everything how you like and install. That will usually fix it if you're running into that specific issue.