Will I lose my custom domain if I downgrade and then come back?

Yes you could.

When you downgrade from the PRO Plan to the Free Plan, the custom domain will be removed too. This allows it to be chosen by another coach who may want it.

If you're worried about losing your custom domain, we recommend to remain on an PRO plan. We will not be able to get it back for you if another coach chooses to use it while you're gone.

Thanks

FITR