You did disturb something, and this is a well-known consequence of a stick repair on this controller rather than bad luck. It is also almost always fixable without parts.
The DualSense speaker sits in a moulded acoustic pocket with a thin foam gasket sealing it against the shell. That seal is doing real acoustic work: it stops the speaker's rear output leaking round to the front and cancelling itself. The speaker sits close to the left stick module, so a stick replacement means lifting the board right next to it, and three things routinely go wrong. The speaker comes partly out of its pocket and is not pressed back fully home. The foam gasket gets pinched, folded or displaced, so the seal is broken. Or the speaker's thin wires get routed over the top of it, holding it proud by a fraction of a millimetre.
Any of those gives you exactly what you are describing: audible crackling and distortion, with the speaker testing as electrically present because it is wired fine and being driven normally. The headset jack being perfect confirms the audio path up to the speaker is healthy, which narrows it to the speaker's physical mounting.
So open it again and check, in this order: the speaker fully home in its pocket with the gasket flat and uncreased all the way round; its wires routed in their channel and not over or under the speaker body; and the connector fully seated on the board. Then make sure the shell closes without tension, because a speaker sitting proud will also hold the shell apart slightly, which you may be able to detect in a housing tension test as uneven flex on that side.
If the gasket is torn or badly deformed, a replacement speaker assembly with its gasket is an inexpensive part. And one thing to avoid: do not add tape or padding around the speaker to pack it in. It changes the acoustic pocket and makes the distortion worse rather than better.
