Figure I would try this again, since I never got any sort of reply last time.
The URL for automatically placing a marker no longer works as advertised.
For example: https://www.windy.com/?5.167,115.278,7,marker no longer places a marker on the screen. The map loads in the correct region according to the specified lat/lon, and the appropriate zoom (in this case 7), but the pin does not get placed.
What I'm noticing then is a local forecast box in the upper left corner (the link I'm using is not local). I click on the map and no marker is placed, but the local forecast box disappears. I click again (after the forecast box disappears), and the marker finally places. Toggling the forecast box off in settings does not fix the problem.