This popup was recently introduced in PR-2174.
I don't know exactly why, but voyager prompting me that I'm about to lose my progress was sort of strange to me in the context of scrolling on lemmy.
I understand why someone wants such a feature, but IMO this should be turned off by default and available as an option.
I personally think this popup is not a great UX, and the text ("lose progress") is unspecific.
It would be smarter to be able to return to the last feed and position with a simple gesture. Or allowing an option to hide posts that were shown during the last visit.
My desired outcome for this thread is to get some feedback. Apparently, most people here like this change, so I am not going to do anything further.
One of the developers told me it's impossible to return to the last feed position. I don't know why, but, I'm not a programmer. I don't doubt it. It was possible with Reddit clients. Could be something Lemmy hasn't implemented, or hasn't implemented yet.