Is it possible to backup individual custom cards prior to updates? Recent experience with an updated custom card has made me a bit nervous about committing to an update without having the ability to reverse the update.
Are you using HACS to install & update custom cards?
If you experience that an update is undesired - download a previous version with HACS.
Card updates should not change your card config. It is left up to you to do this if there are breaking changes. So as Ildar said just reverting to the previous version of the card should fix any unforeseen issues.
You can copy the card YAML to a text file before the update if you want to be “belt & braces” sure.
The yaml configuration of the card is not the issue. Some cards get updated and require changes to the yaml configuration in order to work. Even when those changes are made, the way the card displays is different and undesirable.
I am using HACS to install custom cards but I don’t see an option to load previous versions.
Then fork the repository and maintain your own version of the card.
Cannot give an exact screenshot, away from a PC, but it is like this: in HACS select some card - in menu select Redownload - in a popup there is a dropdown selector where you can choose a previous version.
A suggestion: reduce a number of custom cards to a really necessary ones.