Process version is set in LRTimelapse to version 4 (10) or even 3 (6.6) - currently in Lightroom is version 5 (11)
There is no way to set the process version in LRTimelapse (or I didn't find it).

In the attached PDF file I documented the behavior step by step

Lightroom Classic 8.4 / Camera RAW 11.4
LRTimelapse 5.2.2 Build 577

Why is this a problem? As soon as you edit a keyframe in a newer Lightroom version, it will usually set the process to the latest. LRT will then take it over for all images during the auto transition.

It is a problem because this is changed arbitrarily and for no apparent reason. Also, this change may not be noticed.

This has always been like that. LRTimelapse cannot know, which Lightroom version you are using. It's initializing the images with a default process version and leaving it up to you, which Lightroom Version you are using or which process version.

Thanks for the answer! Then my assumption that the process version is read from the already existing XMP file was wrong, because this information is not in the XMP file at this time.