I am using Lrtimelapse for the first time with my Sony A7R III.
There are very strange behaviors between the phases Lrtimelapse / Lightroom
I have the feeling this is coming from the preset masks
Does anybody had some kind of experience of this ?
I didn't find any thread on the forum

You need to install the latest Adobe DNG converter and the latest Lightroom. Then everything should be fine, if you follow the advices from the tutorials / instructions about the masks.

Thank you for the answer.
After tests the problem is not generate by your software.
I was shooting a moon timelapse and I have a too large dynamic range, trying to keep a little information on the bright moon and in the dark landscape in the foreground, I pulled up too much the shades, and my A7RIII seems to have a high instability (incredible variations of color dominant, noise, density) in the deep shade which are only bearable if you keep them in the absolute black, to pull up the shades amplify in an amazing proportion the problem.
I don't have such a problem with my Canon cameras, I have noise but not such variations from a picture to the next one.
For the same reason I gave up using my GH5 Panasonic for timelapses, I had the same problem of instable shades but even in less dark parts of the picture.
I would be curious to know if anybody else has the same problem or if I am just very unlucky...

Check out the Expert Tips Video #5 video, it could be a similar effect you are experiencing: https://lrtimelapse.com/tutorial/expert

Gunther your are a genious !!!! I learned so much !