Inconsistent result depending on random/small variation in a Markdown file

[ccoVeille]

Check for existing issues

• Completed

Environment

Linux
Homebrew
vale 3.4.2

Describe the bug / provide steps to reproduce it

I'm testing a rule to detect GitHub case and suggest fixing it

Here is the rule

---
extends: substitution
message: Use '%s' instead of '%s'
level: warning
ignorecase: true
swap:
  GitHub: GitHub

Here is a test file:

github_test2.md

http://github.com bar

[github](#whatever)
[github1](#whatever)
[github.](#whatever)

https://jwodder.github.io/
http://github.com

whatever

Code reports

• github.com bar because he wants github.com (not convenient but not related to my bug)
• [github](#whatever) as it should be [GitHub](#whatever) ✔️
• [github.](#whatever) as it should be [GitHub.](#whatever) ✔️

github_test3.md

http://github.com bar

[github](#whatever)
[github1](#whatever)
[github.](#whatever)

https://jwodder.github.io/

http://github.com

The only difference is on last line whatever was replaced by http://github.com

Code reports differs:

• github.com bar is still reported ✔️
• [github](#whatever) is reported as it should be [GitHub](#whatever) ✔️
• [github.](#whatever) is no longer reported 🤔 🐛
• https://jwodder.github.io/ is reported as invalid 🤔 🐛

Now let's change slightly

bar

[github](#whatever)
[github1](#whatever)
[github.](#whatever)

https://jwodder.github.io/

http://github.com

So the on first line github.com was removed

Code reports differs again and seems normal:

• [github](#whatever) is reported as it should be [GitHub](#whatever) ✔️
• [github.](#whatever) as it should be [GitHub.](#whatever) ✔️
• https://jwodder.github.io/ is no longer reported as invalid 🤔 but it's what I would have expected

[ccoVeille]

Here are the files

github_test2.md
github_test3.md
github_test4.md
GitHub.yml