Strange, I am running it on a Snapdragon 8 Gen 2 (Z Fold 5), and it's totally fine for me. (If anything, it's a little too good at staying in the background; if you have private tabs open it insists on persisting in memory.)

Not saying your issues aren't real, but rather maybe there's another app or your manufacturer's flavor of Android that's causing the issue (like those aggressive background killers).

As for Edge, I used to be a big fan, but when they finally introduced history and tab syncing in 2021, it didn't have E2EE, and it still doesn't, which I find inexcusable. All the other major browser vendors offer it, even Google (though you have to opt in).