With the latest release, most likely since JENKINS-59959, the concurrency limit is no longer checked against the pod templates count. I have multiple pod templates in my environment and in 1.26.4 the concurrency limit is correctly calculated per template - in 1.27.1 i don't get my pods spawned anymore as the limit of the template is checked against the total number of pods. At least that's how it looks to me after a lot of testing

Reproduction:

add at least 2 pod templates

set a concurrency limit of 1 on  the first and a higher one on the other

concurrency for the whole cluster above the two limits

spawn some pods of the second template

-> a job requiring a pod of template one does not spawn until no other pods are live