how to control steam update size?

I have a small app (~600mb). The levels of the game are in a single data table. when I add a new level and update the game on steam I get 300mb update. I understand that with games in hundreds GB this is a tiny update, still I would expect it to be a few mb only. In this case adding a bunch of numbers to a data table results in half the game download. I assume I do something incorrectly and I’m looking for an advise.

I followed this:
https://partner.steamgames.com/doc/sdk/uploading
but in my case I get a single pak and I suspect that the entire pak is in the update.
what is the best solution to minimise it? can I somehow force much smaller paks? or control what goes to what pack manually so I can combine frequently updated parts of the game together?

I have no encryption or even compression turned on for the pak files at the moment.

I tried to disable pak files but it seems that the setting “use pak files” in project properties is not making any difference to my project. full rebuild (after deleting all intermediate files too) still gives me the same end product with “paks” folder and large “ucas” file in it.

can I make it better?