That was my impression. Meuwly has wanted her to try the 800 for a few years. Bol mentioned that in several Diamond League press conferences. She was reluctant and would say things like, "Stop putting ideas in his head. It's too far for me."
Apparently she doesn't like sprint training. I think that played a major role in the switch. Bol realizes she won't have to do as much short sprint work while preparing for 800. Also, the 800 probably provides an additional Olympic cycle. As 400 hurdler she would be prime through 2028 but in serious decline upon Brisbane 2032. A middle distance event has considerably greater prospect of extending four more years, other than greater risk of injury. Bol is not the most agile. I expect she will fall more than once if she sticks to 800.
The Dutch travel to South Africa three times every season...after Thanksgiving, after New Year's, and after indoor season. They are transparent on Instagram. I suspect that's when we'll get a glimpse of Bol's training regimen, especially if she and Saalberg are doing one thing and the pure 400 group something else. Normally the 400 group does lots of hills training.
Netherlands media always travel to South Africa briefly and do articles and videos on the Meuwly group. This topic will certainly be a focus.