After several experiments, I think I understood what was going on and this is not a bug of distributions. This is an assumption. This mode of operation of the fan is chosen by the laptop software itself, simply in response to the nature of the work. He sees that I use it quite actively and starts turning the fan more. That is a kind of adaptive mode. And given that the installation of the system and software is a rather loaded mode, it turned out that I saw a working fan. And when the new distribution was launched after some downtime, the fan worked exactly the same as on native ubuntu. Just the nature of use)).
Hello. I have Latitude 5401 with ubuntu 18.04 preinstalled. I would say that it works fine on this system and I was more than satisfied with it.  But, this version is going "Out-Of-business")) and I decide to upgrade it to 20.04. Every function, menu or key works fine. Except one thing. Fan control.  It may seem that I'm nitpicking, but in my opinion a significant change in the behavior of the cooling system is noticeable.  On ubuntu 18.04 fan starts only when there some load and temperature go more then 55C-60C. After some time of idle, temperature goes below 40-45 and fan stops working. I do not work with high loads. Most of the time it some browser and few terminals with ssh. Even without fan temperature were 45-50C most of the time But after upgrade to 20.04 i noticed that fan remains working on 2400RPM even in such "idle mode". CPU temperatures are 38-42C. Most of the time it is AC powered. EFI firmware settings are the same as before upgrade. I have tried to make clean install of 20.04, 22.04,  KDE NEON, Linux Mint 21.1 (22.04 ubuntu base). Every time behavior is the same. The only distro that has behavior like old ubuntu is Fedora 38. configurations of thermald and tlp I have moved from old system to new - no changes. I assume that the system optimization that dell + ubuntu did for 18.04 has a significant effect. But the question is what exactly and is it possible to somehow transfer it to a more recent system?
Dell latitude 5401 fan control after ubuntu upgrade from 18.04