Intense triceps DOMS after L-sits?

I have just recently begun an SSC with L-sits, planches and levers. Yesterday I did 10x6s l-sit holds before my 12 set weighted pull up workout. Today I was surprised to find that I have more DOMS in my triceps than in my biceps and lats! Is it normal for the l-sit to be hitting my triceps so hard, even though I do weekly weighted dips? I also find it difficult to have my back curved and my hands in front of my hips during the position like in the examples in the book. I find my chest just naturally juts out and my black automatically flattens (sometimes I get spine pain because the 'flattening' is so intense!)

What's going on? Should I continue to practice the exercise?

Any help would be much appreciated, thanks.

Normal. The spine 'pain' is your traps/rhomboids working really, really hard along with your upper paraspinal muscles and perhaps serratus posterior superior.

The triceps is normal, you are using the long head which is not what you normally use for dips. It sounds to me like you are performing the exercise fairly well, a lot of people don't. Of course, shirtless video would tell us for sure, or a sports bra if you're a female.

Be careful with your volume, you are working new parts of the muscles. I would suggest that you start off with maybe 3 sets of 6s, if that's what you want to do (6s sets, I mean) and add a set every week or two. Give your body time to adjust, don't just dive in with 10 sets on any of the FSP. That's a recipe for trouble!