I would argue QPR updates are functionality and subject to the 6 month test.
I would also argue a closed source release in August 2025 would start the first 6 month timer (February 2026) and the source code release to trigger another timer (if they differed in any way between the closed source release).
A lot of this law is abstract and only if the EU challenges Google's approach would it be decided how it's meant to be applied in reality.
I believe QPR includes security fixes as well, which should trigger the 4 month timer
Your comment seemed to imply that a source release would trigger a different timer than a binary release, which is explicitly covered as the same thing in the law - for both the 4 and 6 month timers.
I would also argue a closed source release in August 2025 would start the first 6 month timer (February 2026) and the source code release to trigger another timer (if they differed in any way between the closed source release).
A lot of this law is abstract and only if the EU challenges Google's approach would it be decided how it's meant to be applied in reality.