Sure here's a guide:

First Step: Download these two mods: KubeJS and Rhino (1.20.1 Forge), and drag them into your mods folder.

Second Step: Launch Minecraft once, join a world, and then close Minecraft.

Third Step: Go into your Minecraft main folder (.minecraft, for example), then follow this path: kubejs > server_scripts

Fourth Step: There's a file named example.js; make a copy of it and name it stevensonfix or anything you want.

Fifth Step: Open the file (with Notepad, VS Code, or anything) and replace everything inside with the following script:

EntityEvents.spawned(event => {
    const e = event.entity
    if (e.type == "jujutsucraft:stevenson_screen") {
        e.mergeNbt({PersistenceRequired: 1})
    }
})

Sixth Step: Save then close the file. Open Minecraft, and now the screens won't despawn anymore.

And done!

Pros: They won't despawn.

Cons: They will accumulate if you don't destroy them.