I finally managed to resolve my issue.
Suspecting there was a plugin conflict, I used a Site Health Check plugin to disable all plugins in “troubleshooting” mode, and the gradually brought them back in one by one to see where the error occurred.
For me, this error returned when Image Rotator Widget (https://www.wordpresspluginfinder.com/dk-new-medias-image-rotator-widget/) was active. I believe this is due to some kind of conflict across both plugins with JQuery, but I don’t know enough about it to explain the specifics. I’m just glad to finally have the payment gateway operating again! ??
