I'm currently in the UK, but spent most of 2020 living in the US.
I'm going to risk the likely criticism (it's best to be honest when replying to a topic I started!) and admit that I've continued hooking-up to much the same extent as pre-Covid. Not trying to say that this is ethically the most defensible position, but there we go. I will note that I don't have any particular carer responsibilities for elderly parents or others who are medically vulnerable, which is an understandable reason why many have changed their habits.
As a regular attendee at group sex events, this has changed for me, in the sense that the regular official parties and bathhouses are closed. But I haven't had any difficulty finding quite a few unofficial/"underground" events to attend in both the US and UK. These aren't advertised, you have to be invited, but I know a few guys in the porn industry who have contacts for these types of parties. One thing that is notable is these underground parties seem to be a lot piggier and hardcore than the typical official event prior to Covid - possibly selection bias that it's mainly the most piggy guys that are still attending things like that?
Also, at least in the US, the extent to which underground events are happening seems to vary a LOT by city and state.