What is this strange squiggly line character, and why did it suddenly start appearing in my documents?

Thank you. You are correct in that it had something to do with spelling, but that is strange, because I have always had automatic spell checking on.

I then went to Tools, Spelling… At one point the checkbox, the space and the period were present in the box and I pressed “Ignore All”. Now they are all gone!

Thank you for leading me to a solution. I am still confused why it suddenly appeared, but at least I do not see it in a document I used all the time, so I am happy at this time.

Again, thank you.

This strange squiggly line character between the check box and the period, suddenly started appearing in my documents. What is it? Why is it there?

How do I get rid of it?

It also seems to appear whenever I have two spaces in a row.

I have had a check box, a space, and a period in my documents for years and now I get this:
image

Thank you very much for your help in answering my question.

Here is information on my system:
System:
Kernel: 5.15.0-72-generic x86_64 bits: 64 compiler: gcc v: 11.3.0 Desktop: Cinnamon 5.6.8
tk: GTK 3.24.33 wm: muffin dm: LightDM Distro: Linux Mint 21.1 Vera base: Ubuntu 22.04 jammy

LibreOffice:
Version: 7.3.7.2 / LibreOffice Community
Build ID: 30(Build:2)
CPU threads: 12; OS: Linux 5.15; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
Ubuntu package version: 1:7.3.7-0ubuntu0.22.04.2
Calc: threaded

Perhaps you accidentally pressed Shift+F7? Try press it again or choose Tools-Automatic Spell Checking

Have a look at your settings in Tools - Options - Language Settings - English sentence checking