Lightroom consumes all memory and then hangs

Good morning!

It is me again, with my still unsolved problem. That is from some month ago:

I just have it on my second, brand new MacBook Air. The first one had 16GB of RAM, the current has 8GB of RAM.

Start LR, wait 5 seconds: 45GB of System Memory is eaten up. I can not access Prefs or anything in the App.

I am back, with two new computers: One MacBook Air M2, 24GB RAM, and one MacBook Pro 16" with 32GB of RAM. On BOTH computers I can NOT run Lightroom. Classic yes, Lightroom no. After several seconds there is a message, that no system memory is available. The Air ist restored from a backup, the 16" ist fresh out of the box and basically empty. Urgent help needed! 
Thanks in advance
Wolfgang