Four spellings of one campaign is the usual symptom of having no written rule. What works in practice is boring:
- One short document with the allowed values for
utm_source and utm_medium (for example newsletter, email; facebook, paid-social) and a pattern for utm_campaign.
- Lowercase only, hyphens instead of spaces and underscores. GA4 treats
Spring_Sale and spring-sale as different values.
- One place that builds the links: a spreadsheet with a formula, or a small form, so nobody types a URL by hand.
- Never put personal data in a parameter; the URL ends up in reports, logs and other people's screens.
The article UTM parameters: naming conventions that survive a year of campaigns has a ready-made pattern and a spreadsheet layout.