Not all users have the same problem but I think that App Lounge can sometimes get stuck because something “impossible” exists in the Update list.
I gave a list of things to try here App Lounge installs fail at 100% - FP6 Android 15 - #2 by aibd
I noticed
Currently if fp3 official users just jumped two Android versions (a13 to a15) then app-lounge requests for app updates will be “unusual” as far as the remote server sees things. This could be another cause of “something impossible in the Update list”.