No, I am a watchOS app developer and I know how the OS handles background activity.
An app has just a limited time per day do have some background activity.
If an app eats to much CPU or RAM, or storage access, it's killed.
I have Watchla, it consumes nothing on my watch (that's why you have to run it manually, it stays a very limited time in bg).
Coincidence is not consequence.
Only apple system services (music, podcast sync, localization, health sensor, data sync ...) can eat battery in background, 3rd party apps have a very, very limited background activity budget
You can laugh, but it's better to read ...
Manage background sessions and tasks.
developer.apple.com
The delivery of background tasks and the allocation of background execution time are completely up to the system. When making a watchOS app, schedule background updates based on these limits, and prepare for background task throttling. Understanding the limits helps you better design your app’s background update strategy.
To prevent background tasks from using too many system resources or excessively draining the battery, watchOS controls how often and how long background tasks can run. When scheduling background tasks, the system may:
- Give each app an individual allotment of background execution time. The system only triggers an app’s background tasks when it has time remaining in its budget.
- Throttle background tasks when system resources are tight. Even if individual apps have the budget for tasks, the system doesn’t trigger background tasks when the device’s battery is low or the system conditions are poor.
- Throttle background execution when the user is performing high-priority activities, such as exercising or navigating.