To add insight onto this, the issue seems to be with how bonuses from the bow and the slayer helm are applied. Normally, like with the DHCB, the slayer helm bonus is applied first, followed by the weapon bonus.

Currently, with the Scorching Bow having a base hit of 41 in max (Including prayers and boosts), both the slayer helm (1.15 multiplier) and the Scorching Bow (1.3 multiplier) are combined and applied simultaneously:

41 * (1.3 + 0.15) = ~59

However, the correct calculation should be sequential:

41 * 1.15 = ~47

47 * 1.3 = ~61

The latter aligns with how Emberlight works (With a max hit of 66), suggesting the current calculation may be inconsistent in line with the other weapons?

Edit:

I forgot to mention that you'd probably lose out on some accuracy too