Updating 'indexed' attribute of event during contract upgrade

Is it possible to partially update an existing event defined in a contract ? As i understand, events are not stored in as storage variable and act more as an abstration to the logging feature of ethereum. Hence would it be possible to add or remove the 'indexed' attribute from an existing event:

Event before modification:
event existingEvent(uint256 amount, string indexed entityName, uint256 timestamp);

Event after modification:
event existingEvent(uint256 amount, string entityName, uint256 timestamp);

:computer: Environment

Truffle v5.4.6

You can add or remove indexed, it doesn't corrupt the storage layout, but it's a breaking change that is going to break any client that is observing those events. The event signature remains the same, but the log needs to be decoded differently (indexed parameters are in log topics, and the rest are in the log data).