Looks to me like blockage.
Last weekend there was a 160m contest. On Friday night lots of loud EU stations, hard to work until midnight, easy early morning on Saturday. On Saturday way fewer EU stations, and almost none early morning Sunday.
Once I went to Lesotho for a week as 7P8NO, hoping for many QSOs. But there was a nearly total HF blackout, and I did 5 QSOs in the first five days (all African). The blackout ended the day of the departure, and I made 90 EU and JA QSOs in one hr that morning.
Ignacy NO9E