According the the Boston Globe, a historic trolley at the Boylston subway stop was vandalized. I only know of a Type 5 sitting there, imprisoned since probably the early 1990s. There may be a PCC or something else on that track. Three average suburban looking kids were caught on security cameras and they are looking for them.
https://www.bostonglobe.com/2023/11/28/metro/historic-trolley-vandalism/

Perhaps this will be the straw that results in change of this equipment going to a proper home.

The news sits behind a paywall for the Boston Globe.

Paywalls usually have a 1 to 2 second lag time. You can hit Cntl-A, as soon as the page loads, then hit Cntl-C, then paste the content to a document editor to read and see the photos. In this case, there was not much more than what I reiterated, except the photo of the young white men, and the police hotline number. No photos of the vandalism loaded for me.

There are two historic streetcars at Boylston Station. PCC No. 3295 belongs to the T and was the car vandalized. There is also a Type 5, No. 5734, which belongs to the Seashore Trolley Museum and was not vandalized.

Here's an article without a paywall. As the article notes, this has happened before and the MBTA did a nice job cleaning up the graffiti.

For more info and background on this equipment, there's four pages of discussion in the MBTA forum on Railroad.net about both the 2014 incident and this latest one. (I don't see a rule against linking to other forums, but I apologize if this isn't allowed.)