Try add game and steam to exception rules, some even need folder access for thirdpart app in windows document folder where game config is.

And no i did not look up, if your game use that area.

You can find old games that dont start because AV app block it today.
its like the new normal, games in the past can have a startup issue.

You're better off asking in that game's discussion hub than Steam Help and Tips.
Here ya go Liftoff from the store page.
https://psteamcommunity.yuanyoumao.com/app/410340/discussions/

You can find several game devs and other apps even steam, tell user that your personal Security app is not our problem, in what you block or not.

They have tried over 20 years to help ppl, they have made FAQ to help with it,
even seen a steam user say i will not disable or test or make exception rules,
this is why its not there problem its a user own choise to deal with it,
its find you send them to own game Forum, still require soneone know whats wrong if this is the problem,

But technicaly noone has to help you with your security app issue if this is the issue.
So steam own game forum is not support for your dealing with it.

To many helper send them to own game forum, game moderator there can lock your post because game devs is not responsible for your security app issue,

i and other have seen this in total war shogun2, make sure its not a own app security issue.

gl with it.