The problem

When display trackchanges is unchecked or trackchanges are invisible to the user in some cases it is hard to delete character if it is surrounded by deletions. This is because internally from the editor perspective when track changes are always there, they are just invisible for the user.
For example we have the following markup in editor

Hello worl<del>space</del>d

If "Display tracked changes" is unchecked - for the user in the editor it will have look like

Hello world

Now let's imagine we want to delete the word world to later type something else insted. So we place the cursor to be after the letter d and start pressing backspace.
After the first press letter d is replaced with <del>d</del>, and then we have the situation when visually it looks like the cursor is placed right after the letter l, but actually from the editor perspective it is between <del>space</del> and <del>d</del> so next backspace button press doe not delete letter l as the user would have expected, but it is moved internally to be between c and e inside the <del>space</del>. Next backspace press moves cursor to be between a and c and so on.
So to actually delete letter l and to be able to further delete worl after deleting d user needs to press backspace 5 more times because the cursor need to go through the whole deletion.

From the user's perspective it may look like some characters are not deletable.

This is not applicable when selecting part of the text and deleting with backspace or del keys. In this keys always what is selected - deleted.

Solution

Need to fix this behavior and in case the "Display tracked changes" is uncheck or user can not see tracked changes by the settings - deletion should work as if there were no hidden deletions in between.