According to an earlier post back in February of this year (2021):
“Manjaro’s LTS kernels follow the upstream kernel.org LTS. So yes, 5.10 will be an LTS in Manjaro.”
And according to kernel.org:
Yet according to Manajro Settings > Kernel, it does not denote 5.10 as an LTS kernel?
(It also does not tag it as “recommended”, like it does with the previous three LTS kernels.)