When I use a new-line the cursor is displaced by at least 10 spaces

[francisco-lafe]

Hello.

This is a weird error and I don't know if it's OMP or my custom theme (attached). mytheme.omp.json.zip
As you can see, on the same line I have the "cursor" on the beginning of the line, but if I do SHIFT+ENTER (Newline) the cursor gets displaced by a lot:

What is going on?
Windows Powershell:

Thanks.

[JanDeDobbeleer]

Which shell is this?

[francisco-lafe]

Sorry, I forgot to specify.
I'm using Windows Powershell 5.1

[francisco-lafe]

Refer to:
#2395 for solution