The package definitions are separate for each branch. The wifi drivers and wifi firmware blobs offered for in the ancient releases (like 19.07) have not been updated regularly...
19.07 offers older blob than master, like you have noticed.
https://downloads.openwrt.org/snapshots/packages/arm_cortex-a15_neon-vfpv4/base/
https://downloads.openwrt.org/releases/packages-19.07/arm_cortex-a15_neon-vfpv4/base/
You need to use the respective driver targeting the respective OpenWrt branch, but you might be better off by loading a newer ath10k firmware blob from master, even for 19.07. I haven't tested it myself, but to my understanding the ath10k blobs have no direct link to a specific driver version. (QCA even has several concurrent variants with separate versioning)
The whole ath10k driver system is pretty confusing with several wifi chip firmware blob variants, mainline/ct driver variants etc.. You are free to try to find the best combination for your client hardware. Sadly none of the blobs or drivers are perfect.
(But situation is still better than with the abandoned mvebu mwlwifi...)