I think having an enabled_at field as nullable timestamp is enough.
If it’s present, it’s enabled. If it’s null, it’s disabled.
It’s a Boolean with context.

If you really need to track the history of a record being enabled/disabled, I’d suggest this should be in another table. With postgres (not sure if it’s all DBs) you could create a trigger that when a record’s enabled_at field is updated, it creates a record in the log table with a from state, a to state, a timestamp, even a role/user.

That way, you could then extract the history of that record if required.
Tbh, if using postgres, you could just make a logging table that stores a JSON of the entire old record, and a JSON of the entire new record.
Would let you rewind the history of a record, see who did what, etc.

Saves having an enabled and an enabled_at where there are potentially multiple sources of truth, or faffing around with arrays, multiple fields, over-pulling data