Since the transition, the slippy map on JOSM (for selecting an area for download) merely shows a grid with red lines, big red crosses and a selection rectangle. It is possible of course to select your area for editing from OGF, so it’s not a deal-breaker.
Comment from Lithium-Ion on 3 October 2021 at 23:08
I think you need to change your TMS link in JOSM to the new one - see here for instructions. Hope this helps!
Comment from ADB52 on 4 October 2021 at 09:00
Ah, brilliant. Works a treat, many thanks.