Mechanical Shimano Deore Disk Brake - How to fix lack of bite/grip
Mechanical disc brakes can work well, but they need to be set up just right for top performance. There are a few aspects:
Pad condition: you have new pads which is good because they will be flat and clean. They can be scuffed lightly with sandpaper to be refreshed when necessary, if a little dirty, or hardened/glazed. They need to be uniformly flat and not worn unevenly, with a matt complexion.
Disc condition: it needs to be running straight/true and free from contaminants like oil, but bedded in, where a fine layer of pad material is transferred to the disc to increase friction. You mention braking 40+ times, this is the bedding in process, but I start doing this very gently and increase the duration and force as the brakes warm up. You might like to clean the disc with ipa alcohol or brake cleaner to reset them, then re-do the bedding in.
Pad positions: the inboard pad is fixed in position, but can be positioned with the Allen key adjuster (5 mm) on the inboard face of the brake caliper. It must be as close to the disc as possible without rubbing the disc; you can find the setting where it rubs gently and back off one click. The minimal gap ensures the disc doesn't get bent much out of vertical when the floating pad operates. This is critical for maximum power. If you can see the disc getting flexed sideways a lot then something isn't right. This is something to monitor and adjust in use, to account for pad wear as it is not automatic like with hydraulics.
Cable tension: finally the cable tension is set up. This is to give acceptable lever travel, but it has the least effect on braking power, the previous points are more relevant to power. You could set this up to your preference of early bite point or late bite point, but well clear of the bar when the lever is pulled. The previous points are more effective in getting sharp brakes than the cable tension, and you can set it with the pinch bolt, in combination with the barrel adjusters.

If any of these aspects are not set up optimally, the braking performance does drop noticeably, so work through them methodically. Finish with a bedding in procedure which is gradual and patient, to really get them sharp.
From your comments, it sounds like the inboard pad is out of position and causing your problem. if that rotor is pushed out of vertical any more than necessary, then the contact is reduced and power is lost. You need to locate the pad adjustment screw and get the fixed pad closer to the disc.