Importantly though, if this is true, it's a real sign of Russian willingness to compromise alongside indicating that they’re willing to acknowledge their weaknesses.
If true, they’re signalling that they can’t afford to lose their Black Sea Fleet, so Ukraine could say, "Okay, as long as there are assurances from your side."
They should be that the BSF stays in port and can't be used as a base for PGMs (missiles etc.) and aircraft. This could add security and allow grain movements.
The caveat being that if Russia do not agree to or maintain the agreement, Ukraine has carte blanche to attack their fleet at will. Will Russia agree to this?
Probably not, but at least it's a conduit for discussion and Ukraine has increased legitimacy to attack Russian assets.