The www.defensie.nl website confirmed this. The site write the following:
Airmen and ground personnel of the Royal Netherlands Air Force train from Monday 9 November to Friday 20 November with their F-35 fighter aircraft from Volkel Air Base. The exercise of the Leeuwarden F-35 squadron at Volkel is part of the step-by-step plan that will lead to an initial deployment capacity of the squadron at the end of 2021. The relocation exercise is during the period in which training is also carried out in flying in darkness.
They ad the following too
Due to operational reasons or unforeseen circumstances, the above planning may be deviated from.