16 years after the United States FAA approved 600 kg Light Sport Aircraft, EASA (the European Safety Agency) is finally allowing 600 kg Ultralights which are the equivalent of USA Light Sport Aircraft in Europe. (See this article for more background on the topic)
The way regulation works is that EU Member states need to Opt-out of EASA managing the aircraft and take them under their own National management. Most National regulators seem keen to opt-out as there is a lot of pressure from their pilot and manufacturer associations to do so.
Ultralights already flying at lower MTOW restrictions will only be able to upgrade their weight class if they are recertified. Some National regulators are not allowing this recertification while others welcome it. Finland where I live has chosen not to allow the recertification.
Implementation of this new regulation may take some time within the national member states that opt- out. The expectation is that they will have it in place during early 2021. Aircraft manufacturers will have the option to opt-in to EASA certification of 600 kg aircraft under CS-LSA certification if they choose to regardless if their National regulator has opted out.
Here is the Actual Regulation
In EASA (EU) 2018/1139 Basic Regulation Article 2 (8)
A Member State may decide to exempt from this Regulation the design, production, maintenance and operation activities in respect of one or more of the following categories of aircraft:
(a) aeroplanes, other than unmanned aeroplanes, which have no more than two seats, measurable stall speed or minimum steady flight speed in landing configuration not exceeding 45 knots calibrated air speed and a maximum take-off mass (MTOM), as recorded by the Member State, of no more than 600 kg for aeroplanes not intended to be operated on water or 650 kg for aeroplanes intended to be operated on water;
(b) helicopters, other than unmanned helicopters, which have no more than two seats and a MTOM, as recorded by the Member State, of no more than 600 kg for helicopters not intended to be operated on water or 650 kg for helicopters intended to be operated on water;
(c) sailplanes, other than unmanned sailplanes, and powered sailplanes, other than unmanned powered sailplanes, which have no more than two seats and a MTOM, as recorded by the Member State, of no more than 600 kg.
However, as regards the categories of aircraft referred to in the first subparagraph Member States may not take such a decision concerning aircraft in respect of which a certificate has been issued, or has been deemed to have been issued, in accordance with Regulation (EC) No 216/2008 or with this Regulation, or in respect of which a declaration has been made in accordance with this Regulation.