But why is that?

Okay, thanks for the advice to simply hide the notifications.
But I'll rather leave the notifications to stay informed ;-)

To the graphics driver:

I initially opted for the free graphics driver. However, I have since realized that the font is not displayed so well on some websites. So I decided to install the Nvidia driver. "nvidia-detect" showed that I should install the driver: "nvidia-tesla-470-driver". The installation was actually problem-free, but in the end there was an error because "nvidia-persistenced" could not be installed. Even after restarting the computer, this remained unsuccessful. So I decided to uninstall this service from nvidia. This was crowned with success, because the "nvidia-persistenced - Service" could be deleted without any problems. Now Nvidia works without any problems.

Another problem that did not exist under Chimaera:

When starting the computer, the following is now written in several lines:

ima: error communicating to tpm chip
ima: error communicating to tpm chip
ima: error communicating to tpm chip
ima: error communicating to tpm chip
ima: error communicating to tpm chip

What is this error and how can I fix it? I did not have such an error under Chimaera.

I have now looked at lxappearance and obconf and indeed there is a theme there, that is called Clearlooks-Phenix-Sapphire. But the theme looks slightly different from the conventional Clearlooks theme. But under icons there is no Sapphire theme.

And if there are no more user-defined themes in the future, then all we have left is Clearlooks ;-)

I have now taken a closer look at jgmenu. It seems to work fine. I installed jgmenu from Daedalus packages on Chimaera. After a few tries, I managed to get it to look good by my standards. Actually I wanted to make it even better, but somehow it didn't quite work out yet. In that area obmenu was already much easier.
I have a submenu, but how can I actually make another submenu from the submenu?

I used now the old XML obmenu file parallel with jgmenu. Jgmenu is anchored in the Tint2 bar. What else I noticed is that jgmenu can also read the XML file without any problem and can also display it just like obmenu. I like that jgmenu has a search function integrated. That is already very practical. I have set it so that jgmenu uses the same optics settings of obconf and tint2.

Ah good to know that it no longer works.

I also miss obmenu. Unfortunately, there isn't really an alternative in Devuan's packages. In the virtual machine I looked at jgmenu under Artix. At first glance, quite okay, but it is not as simple as obmenu. I will continue to use my XML file and modify it as needed and wait until a decent replacement comes along.

I have fixed the internet problem. I then started a trial. I installed Iptables, UFW, again. But after booting UFW was not activated. Then again removed Iptables, Nftables, UFW. This time installed only Nftables. After that UFW. UFW installed Iptables as a required package. After that UFW activated and after booting the laptop UFW was deactivated again. Through the links of Head_on_a_Stick I came to the Firwall Firewalld and its graphical interface Firewall-config. I could not start this firewall, it was always disabled. This firewall seems to be really only for SystemD. Could it perhaps be that Chimaera is no longer compatible with older hardware? My second laptop is a Dell. Although Beowulf was still running fine. Chimaera runs, but UFW seems to have problems with it.

On my first laptop, a Lenovo, UFW also has problems. It's strange that an upgrade from Beowulf to Chimaera suddenly causes problems on both devices.

My output in /var/log/boot looks like this:

Mon May  9 16:57:59 2022: [....] Starting Setting kernel variables: sysctl??7[ ok 8??.
Mon May  9 16:57:59 2022: [....] Setting up resolvconf.../etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /etc/resolvconf/run/resolv.conf
Mon May  9 16:57:59 2022: ??7[ ok 8??done.
Mon May  9 16:57:59 2022: [....] Starting firewall: ufw...Setting kernel variables (/etc/ufw/sysctl.conf)...??7[ ok 8??done.
Mon May  9 16:58:00 2022: [....] Configuring network interfaces...ifup: waiting for lock on /run/network/ifstate.eth0
Mon May  9 16:58:06 2022: ifup: interface eth0 already configured
Mon May  9 16:58:06 2022: ??7[ ok 8??done.
Mon May  9 16:58:06 2022: [....] Cleaning up temporary files...??7[ ok 8??.
Mon May  9 16:58:06 2022: [....] Setting up ALSA...??7[ ok 8??done.
Mon May  9 16:58:06 2022: [....] Setting sensors limits...??7[ ok 8??done.
Mon May  9 16:58:06 2022: [....] Setting up X socket directories... /tmp/.X11-unix /tmp/.ICE-unix??7[ ok 8??.
Mon May  9 16:58:06 2022: INIT: Entering runlevel: 2

No, I have not added my own rules. I use the default setting with UFW. I have already uninstalled and reinstalled UFW several times with all its dependencies. But the error still persists. It is because of UFW that the errors appear. If I disable UFW, then there are no more error warnings. If I enable it, then the errors come again when I boot the laptop. After booting the laptop, however, UFW remains active.

Output:

root@Lenovo:~# ufw status
Status: active

root@Lenovo:~# /usr/sbin/ufw status
Status: active

Output looks like this:

root@Lenovo:~# service ufw start
Starting firewall: ufw...Setting kernel variables (/etc/ufw/sysctl.conf)...Firewall already started, use 'force-reload'...done.

On my other laptop, where UFW is constantly disabled at startup, I removed Iptables completely with its dependencies. This laptop now has no internet connection. With the removal of Iptables was also removed Nftables, Connman internet service, UFW .... . I can't connect to the internet with it now. It looks like I have to reinstall Devuan completely. Or is there another step to establish an internet connection?