Guest users on your Trello board can use the Power-Ups in read-only mode. That means they can see the card sizes, priorities, and dependencies, but they can't modify them. For example, when they click the Set priority on a card, they will see the following message:

Any person who wants to change the values must be a member of the Trello workspace where the board exists. It's not enough to add a user to your Trello board; you need to add that person to your workspace as well.
Related questions
The likely reason is that someone on your team disabled the Power-Up on your board. If anyone on your team enables it, it will be visible again for all team members. That’s how Power-Ups work, either everyone sees it, or no one sees it.
The likely reason is that someone on your team disabled the Power-Up on your board. If anyone on your team enables it, it will be visible again for all team members. That’s how Power-Ups work, either everyone sees it, or no one sees it.
In order to use the Power-Up on your board, the board must have a workspace associated with it. Creating a workspace is easy, just follow these steps to create one.
In order to use the Power-Up on your board, the board must have a workspace associated with it. Creating a workspace is easy, just follow these steps to create one.
Each user must authorize the Power-Up by clicking the Power-Up name at the top of the Trello UI and completing the auth flow.
Any person who wants to use this power-up must be a member of the Trello workspace where the board exists. It's not enough to add a user to your Trello board, you need to add that person to your workspace as well.
Guest users can use the Power-Up in read-only mode.
Each user must authorize the Power-Up by clicking the Power-Up name at the top of the Trello UI and completing the auth flow.
Any person who wants to use this power-up must be a member of the Trello workspace where the board exists. It's not enough to add a user to your Trello board, you need to add that person to your workspace as well.
Guest users can use the Power-Up in read-only mode.
Auth flow does not work in the desktop app. We are looking for options to have this fixed but meanwhile, the workaround is to use the web app for authorization (after which you can use the Power-Up in the desktop app).
Auth flow does not work in the desktop app. We are looking for options to have this fixed but meanwhile, the workaround is to use the web app for authorization (after which you can use the Power-Up in the desktop app).
To disable the Power-Up, open the board menu on the board where it's enabled, click Power-Ups, search for the Power-Up in question, and click Settings. From there, you'll be able to remove personal settings and disable it.
You can find more details about Power-Ups here: Handling Power-Ups
Notice that removing a Power-Up from a board does not close the subscription (if you have one). To close the subscription, see this guide.
To disable the Power-Up, open the board menu on the board where it's enabled, click Power-Ups, search for the Power-Up in question, and click Settings. From there, you'll be able to remove personal settings and disable it.
You can find more details about Power-Ups here: Handling Power-Ups
Notice that removing a Power-Up from a board does not close the subscription (if you have one). To close the subscription, see this guide.