Reddit is the only platform that actually tells you that you are shadowbanned, so at least they are upfront about it, but their appeal system sucks. My friend just appealed every day for just over 600 days and finally got their account un-shadowbanned.

Isn’t that definitionally impossible? If they tell you about it then it’s not a shadow ban.

Reddit doesn't tell you you're shadowbanned. You are thinking of regular banned.

No they don't and if they do tell you that means you have been banned.

"It only took two years for my friend to appeal a Ban"

If you're willing to wait a couple years, I dare say a few services might have changed their minds by then, so it's too early to judge.