So, I think that explanation makes perfect sense – however, even if I comment out the part of the plugin that includes the other version of ACF, then delete the /vendor/acf folder in the plugin (ensuring that only the live version, 5.9.8, is loading), I’m still seeing the issue, so I think it must be something else causing this.
I’d thought that ACF internally already checked if another instance was loaded and ensured that there’s only one version being loaded, no? https://support.advancedcustomfields.com/forums/topic/check-acf-exists-or-not/
