Some ships were upgraded before Covid. The Adventure, Indy, Oasis, all have I am sure. I believe the Serenade of the Seas was in dry dock for 2 or 3 weeks in April but nobody seems to know what work was done.
We just got off the Explorer and it has had sone things upgraded and was in decent shape but needs to major upgrade. It did appear to have new carpet, new modern elevator touch controls and the cabins were in great shape but the WiFi was awful and it needs more dining options in my opinion.