Epinasty tomatos?

Hello,
I came to this group because I googled epinasty in tomatos and Google showed me a thread in this group from 2 years ago.

I experience a weird phenomenon in my container grown tomatos: they curl their youngest adult leaves during night time and uncurl during day time.

I have googled and asked chatgpt and I just can't find any explanation for what's going on.

As I understand it epinasty is about the upper petioles growing at a different rate than the under petioles resulting in a curl. This would also mean grown that way – stays that way.
The curling in my plants however is temporary and night/day depending.

While I know that it's common for many plants in fabaceae to close their leaves during night time I have never head about such things in the nightshade family and I am extremely intrigued and curious.

More background:

I have 8 tomato plants, 4 different varieties, potted into 40l containers with 2 different substrates. All tomatos exhibit the night time curling.
The location is northern Germany and I grow my tomatos in a sun room that has East-South orientation. There is no heater and no source for ethylene. Ventilation is natural: I open a window on the south side and a door on the north side for big ventilation later in summer and currently only the north side door. The sun room leans on the house in the west and thus doesn't catch the afternoon sun torch temperatures as the house casts a shade in early afternoon.

My tomato plants are now in the beginning of their life and are around 40-60cm tall. Across varieties they all are currently developing their first flowers.
They are not waterlogged and not too dry. I have blue and yellow glue traps and they are clear, so no pests. No leaf discoloration, no signs of sicknesses. No stunted growth.

But because the sun room isn't heated April was a bit harsh, we had quite low temperatures that sometimes dipped down to freezing during nights. The sun room however stayed approximately 10 degrees Celsius and dipped down to 8 occasionally during nights. One tomato plant showed a slight purple discoloration in the leaves and I chalk it up to low temperatures messing with the uptake of phosphorus and indeed, as temperatures rose the discoloration resolved itself.

The seedlings did not curl during those colder temperatures.

Now as we have warmer weather the temperatures should be perfect for tomatos with around 18-20 degrees Celsius during nights and 25-27 degrees during day time. With the warmer temperatures growth sped up and with the warmer temperatures they started to exhibit the weirdo night time curling.

I would love to hear all your thoughts about it and also if your tomatos do the same?

Also, I am new to growing tomatos but not new to growing plants. I am a trained gardener, have worked in perennial nurseries and as a landscaper. I am however a hands on practical gardener and not a scientist. I love reading about it and I love learning more about the on depth processes but that's not something I know much about.

I am only mentioning this because please do believe me when I say that my plants aren't waterlogged. Chatgpt already refused to believe me when I said that my plants aren't waterlogged.

I have not grow tomatos before because I never lived in a situation where that would have been an option and I didn't encounter tomatos at work.

Do you guys know what may be going on in my tomatos that would cause this nighttime curling? I am so very curious.

It's seriously one of my favorite things in life to keep learning about plants.

Thank you