It may also be a measurement artifact. Looking at the generation by type page,
replyhttps://transparency.entsoe.eu/generation/r2/actualGeneratio...
Everything dropped to zero except wind and solar, which took huge hits but not to zero. I expect those have been disconnected too, as they cannot transmit to the grid without enough thermal plant capacity being online, but if the measurement at some plants of how much they're generating doesn't take into account whether or not they were disconnected upstream they may still be reporting themselves as generating. You can't easily turn off a solar plant after all, just unplug it.
Either that, or they're measuring generation and load that's not on the grid at all.
Probably they are estimates of not grid metered generation assets based on wind speed and solar production, at least in the UK nearly all solar is 'estimated' because it is not measured directly (apart from larger sites), at least in real time.
replyRooftop solar for example just shows as a reduction in demand, not 'generation' per se.