TL;DR
Have a version filter when looking at user uploads on the Mod Portal.What?
If you look at a modder's page for uploaded mods, it will list everything unordered, like look at this one:https://mods.factorio.com/user/Quezler
Some 2.0 then 1.1, then 2.0 again, etc.
So similarly the browse page there could be filter for at least Factorio version and maybe Space Age.
https://mods.factorio.com/browse
Maybe the best would be to have it merged with the browse page, so browse has a section for search by User.
A dropdown with all users would probably be a performance issue, a freeform textbox could suffice.
Or if it's undesirable development then at least sorting them would be useful, so 2.0 mods first, then 1.1.