Has anyone tried the "Philip bloom deflicker" trick?
it is a trick for video, but maybe useful for timelapse also?

When doing slowmotion video with fps from 120 and up, you start seeing flicker with some cameras, caused by 50hz or 60hz light.
To fix this in post, you can duplicate your footage in your timeline, and move the second layer one (or more) frame. Set the layer at 50% opacity. This will eliminate the flicker.

I have not tried this myself, but when I have time I will have a try.

Wouldn't that result in a slight ghosting effect?

Some shots might not mind that, others might.

Dunno. Worth a try for sure.

Maik Thomas did a video on this. works really well to get rid of birds and other things that are only in one frame. sometimes works for flicker as well

Depends on the shot. Can do wonders, can look horrible.