You are presumably using a hardware keyboard with your iPad, and not the virtual keyboard.
Historically, there’s been a conflict between backspace (often ^H) and delete going back most of forty years, maybe longer.
Here are the available iPad controls: Type with fewer taps - Apple Support
There is no control for (un)selecting backspace-as-delete, and there probably isn’t iPad handling for ^H, for those that are familiar with that.
At present, pending any potential future changes by Apple, you’ll need to use the hardware keyboard arrow keys where those are available. Or tap and hold the display (the magnifier will open) where you want to make the change. Or the trackpad present with most hardware keyboards. Or you can use the virtual keyboard and press and hold the spacebar to trigger the on-screen virtual trackpad. A hardware keyboard might have a mode to control the key behavior, too; of 0x08 versus 0x07F, in ASCII.
Log some feedback with Apple, as they may or may not read feedback here.
Product Feedback - Apple
PS: see the section “Backspace vs. Delete and ISO Standards” for some related history:
https://lowendmac.com/mail/07/0502.html
For more history:
https://vt100.net
This mess goes back a long way.
PPS: i was peaking around 60 WPM on a manual, well before Mavis Beacon. I don’t miss those keyboards. Or the jammed keys. Or the Liquid Paper.