Persistent issue with the charging animation on my Apple Watch

I’ve been using an Apple Watch Series 9 (GPS, 45mm) since December 2023. It’s my first smartwatch, and I chose Apple because I’m deeply integrated into the ecosystem.

However, I’ve noticed a persistent issue with the charging animation—it takes 5–10 seconds to appear after placing the watch on the charger. I’ve logged three service tickets (two last year and one this year). The Apple service center reviewed it and claimed it was "expected behavior," which felt like a generic response.

Interestingly, an acquaintance with a Series 7 faces the same issue. The watch also passed Apple’s MRI diagnostic test, ruling out hardware faults. What’s puzzling is that right after service, the animation shows up instantly with the OEM magnetic charger, but a few weeks later, the delay returns.

I keep my devices in pristine condition, so dirt or grime isn’t a factor. I’m also a regular swimmer—how long can I expect the seals to hold up before water resistance degrades over time?

Any insights or suggestions would be greatly appreciated.

[Re-Titled by Moderator]

Original Title: Delay in charging animation