I’ve checked this on my test site using the latest version of the WooCommerce Stripe Payment Gateway plugin (v8.7.0) and the settings seem to be saved as expected|:
Can you go to WooCommerce →Settings → Payments → Stripe, and enable “Debug Mode” (if this isn’t already enabled):
Once this is enabled, can you please try saving the settings again to retrigger the error, while checking the browser console for any errors? You can read more about using your browser console to identify errors here
Once you’ve done this, please share the following:
System Status Report: you can find this via WooCommerce → Status. Select Get system report and then Copy for Support.
Fatal Error Log: Share a copy of any fatal error log found under WooCommerce → Status → Logs. More specifically, any Stripe-related logs.
Console Errors: Any errors that may be displayed in the console while saving the settings.
Hopefully the console and error logs will log something this time around that could help indicate what’s happening here.