Sitting on this problem for over a week now, no pun intended 😅, but wow I must admit seeing a QR code in there was amazing

but the website that it led me to, kohler.com/toiletservice and ultimately how quickly I found https://www.kohler.com/en/support/help-and-faq/replace-a-canister-flapper-seal what I needed, wow, was the icing on the toilet cake.

Got the stuff

Their version
https://youtu.be/EycBm18o9n8

My version

https://vimeo.com/814079885

Silence.