It's not a trigger.
I'm a web developer. iOS Safari is by far the most painful browser to develop for because of so many painfully dumb things like this they do.
In every case, the solution is for the user to stop using Safari. The hope that Apple would fix Safari, or stop breaking it regularly, died about 10 years ago.
I wish I could help you more with your specific problem. I use (and love!) 1password.
One of the cool things about it is it works across many different platforms which is great for the vast majority of the world who aren't helplessly trapped in the Apple ecosystem. Seeing this problem just leads me to believe that this is one more thing Apple is trying to make an inferior version of that will further trap those poor souls on their platform, not by providing extra value, but by providing less, and breaking compatibility with 3rd party tools, the Apple MO.