The behavior of extra vars behaving differently between 2.18 and 2.19 with AWX in the mix seems similar to an issue I had in 2025. The gist is that I had an AWX job template that would take a datetime input string passed as an extravar; when my execution environment used Ansible 2.18 it took the datetime as a literal string and worked for my purposes. When I switched this same job to use a 2.19 EE, the string would not be preserved literally, but interpreted into a different, incompatible with my use case date time string. The thread was here AWX extra_var for datetimes exhibiting different behavior between Ansible 2.18 and 2.19
Sorry if this isn’t terribly useful, but there was a reply that did elaborate a bit on why the behavior might be happening. At any rate, I’m glad I got to learn about sexagesimals.