Noise between Seat Tube and Top Tube I bought a Trek X-Caliber 9, September last year.
About a month ago it started to do a very annoying sound between the welded junction of the Seat Tube and the Top Tube.

What I have tried:

Switch the seat post and saddle.
Switch the pedals.

I cannot ride with these noises they truly disrupt my mind.

The creaking only shows up when I sit on the saddle, I replaced the saddle and the seat post but the creaking didn't cease. I think the noise is from that area because I've put my hand in there and felt the creaking.
I have cleaned it several times and even if I lower the seat post the creaking continues.

UPDATE: I still have the issue, I am going to the second Bicycle Repair Shop this weekend, But I think it is the left arm crank who's making those noises. But I will keep you updated!   2021-04-23
I suspect that your seatpost is graunching inside the frame as the rider's weight moves about while pedalling.
By inserting the post much further than normal, it will apply a different less-worn part of the post to the clamping area of the bike.  But you've tried this and the noise continues.
So the next cause is that the frame is slogged out already in the clamping area, because of movement of the seatpost and the leverage afforded by the long unsupported length.  You could do the seatpost clamp up tighter, but this is likely to be a short term fix.
Try unclamping the seat post, removing, and then do up the clamp without adjusting it.  Then measure the hole with vernier calipers in multiple directions.  You want to see the same number in all diagonals.  Also feel inside with a finger - it should be flat in-line with the seat tube of the frame, with no detectable curve.
If there's physical damage, you should talk warranty with the seller as soon as possible.
Personally the super-long unsupported seatpost is a recipe for disaster IMO.  I've cracked three frames in decades, and bent multiple seatposts by having them too long and/or too little inside the frame.