I was using 3.7 for a long time, and just got 5.0 (both CD version)
I find i can no longer compile my modem drivers, because they rely on the kernel source.
Also many of the dev libs are no longer available.
I have dial-up, so getting these is very painful (eg. 35Mb kernel source, and my modem only works at 9600 baud, plus then i'd still need many dev libs)
My main reasons for using knoppix were that I am a programmer, yet quite a newb at linux under the hood, so knoppix was
the perfect distro for me. But its not any more, its just the same as all the other 'easy' distros, ie you have to go through the pain of getting dev libs etc, then dealing with dependancy hell.

Dell Precision T5820 Workstation 3.70GHz W-2135 No RAM/ GPU/ HDD/ OS
$179.98
NEW HP Z4 G4 Workstation Xeon W-2123 16GB ECC 256GB NVMe NVIDIA T400 750W Win11
$450.00
Intel Xeon E5-2680 V2 2.8GHz 10-Core 25MB 8GT/s SR1A6 LGA2011 B Grade Server CPU
$7.95
For Parts - Lenovo ThinkServer TS460 Part Number: 70TT-0020UX
$149.99
Lenovo ThinkStation P520c Intel Xeon W-2133 6-Core 3.60GHz -NO RAM/ HDD/ GPU/ OS
$127.54
Intel Xeon E5-2699 V4 2.20GHz 55M 22-CORES LGA2011-3 Server Processor 145W SR2JS
$84.49
HP Z840 44 Core Workstation 2x Xeon E5-2699 v4 - No RAM/ GPU/ HDD/ OS
$594.97
Dell Precision T7820 2x Xeon Silver 4114 2.20GHz 950W No RAM GPU HDD 4x SATA
$354.48
Dell Precision Tower 7810 Xeon E5-2630 v3 @ 2.40GHz , 32GB Ram, NO HDD, NO OS
$239.99
Dell Precision T1700 Workstation Intel Xeon 16G Ram 256GG SSD Nvidia 600 Win 10
$109.99