Big difference in Conversion Tracking

Hello everyone, for a couple of weeks we have had big problems with our tracking integration. In the past, we saw about 70% off our woocommerce conversions in google analytics. (What seemed to be acceptable due to constant ratio- Borlaps Cookie) From one day to the other, this rate dropped to about 30%.
When I looked at Google Tag Manager (i am no expert), I could see a few things:
1. Purchase and Checkout trigger need “/checkout” included in the url Path. But in german woocommerce this is now “/kasse”
2. I integrated the gtm4wp plugin about 3 years ago, and most of the triggers and tags never changed since that time in GTM. Does the plugin automatically update the tag manager settings, if there are any changes in woocommerce? In example if the URL pass changes from “/checkout” to “/kasse” or does this need manuell updates?
3. The “Thank you” Tag is fired correctly in every Test, because it is triggered by custom events. Does this tag only work in GA in combination with other tag i.e. purchase and checkotu tag?

What I don’t understand at the moment, is that if the problem is just the triggers with the wrong /checkout path, why do we still track 30% off all conversions? Shouldn’t it be 0%, because of the missing path, the triggers purchase and checkout should never trigger. There are case when conversions are tracked correctly, but unfortunately we have no idea what this depends on.
Do you have any ideas?
What about updating the settings? Do we have to do this manually?

Many thanks for your help in advance!

Steffen