This is a discussion where you're probably not going to get too many people to change their views on Sanders, one way or another.
First, I think you have to remove Gabriel from the discussion for this topic when talking about the Browns needing to draft a QB. Whether you think Sanders played better than Gabriel or not won't have much relevance with what the Browns decide to do. I don't believe Sanders will be a long term NFL starter, but I do think he is clearly better than Gabriel when at their peaks.
The QB is far and away the most important position, so sometimes what people believe may be irrational decisions when drafting or signing a QB, it's not actually that irrational. Do the Browns believe Mendoza, Moore, Simpson, or whatever other top QB prospects there are, are a clear upgrade from Sanders and are future franchise QB's? I believe if they viewed those QB's like people viewed Caleb, Daniels, Maye, Trevor, Burrow, etc., then they would absolutely see if they could move up in the draft. I don't know if they will end up having the draft capital to do so, and if they make the move, then they'll have drafted three QB's in two years.
If I had to guess right now, I'd say they don't make a move for a QB, and either Sanders or Watson starts next season. Then they will evaluate and go from there, but I don't think they make a big move for a QB.