There are still Linux sysadmin job postings occasionally. Speaking as someone who has some older(10-year) sysadmin knowledge, but has been doing application support for the past 10 years, and is currently looking, I can say that there are occasionally Linux System Engineer postings.
By all means if you see anything go ahead and post it to the list.for me I think it's a combination of things. Both the recruiter and I are older at this. He has his standard clients. I haven't been actively looking since around 2020. I also don't take anything that requires Windows admin skills. My Windows fu is all NT4 and Exchange 5, desktops maybe through W95. "No windows" knocks a lot of them out.