I was monitoring my server today and I saw the following;
04/06 14:59:39 | 'RustCore v2.0.5788' is using deprecated hook 'OnMapMarkerRemove', which will stop working on Sunday, 31 December 2023. Please ask the author to update to 'OnMapMarkerRemove(BasePlayer player, List<MapNote> mapMarker, int index)'
I would edit the plugin myself but I am not well versed in coding.
Update needed
On the bright side there is still a lot of time for them to update this.