San Mai knife bend/warp easily, this is not just TF, over half of my name brand San Mai knifes were not perfectly straight, this includes TF, Kurosaki, Toyama, Yoshikane etc., although to different degrees. It’s not a big deal. Even Shig. will warp overtime & need correction eventually.
It’s easy to bend it back, you can do it by hand over the counter top, but more precisely, I prefer rubber mullet lightly hitting the high spot on the blade lay flat on a cutting board. It’s important to straighten the knife before sharpening & thinning. You might have to do it a few times as the internal force tend to want to bend it back after initial correction.
look at your other San Mai knives, they are probably not perfectly straight either.
Some blade warp, like my TF, the edge & spine bend towards opposite directions, in which case, you may not be able to cure both, it’s more important to keep the edge straight. This might have something to do with TF super high HRC, thus, more internal steel stress. It’s probably much easier to stay flat if it’s 60 HRC, but I love my TF the most even with all its flaws. It’s a project knife for sure, not for everyone.
if your knife is straight, all you need to do is to thin it, even out the high low spots