Spot on with the multimeter advice, honestly i never trust the label anymore. ngl i have this exact same problem and its been driving me nuts for months now. Basically running into these same walls:

• huge voltage sag when i try to pull full rated amperage
• conversion efficiency is absolute garbage on the cheaper cells
• thermal throttling kicks in way too early during fast charging It's like you cant find anything decent without paying the premium tax lately. been dealing with this search for way too long and i still havent found a solid answer yet... just feels like everything is a gamble. definitely sticking around to see if anyone actually knows a pack that hits its specs.

Wait really?? Thats actually super helpful. I always thought it was the other way around.

Anker PowerCore 10000! I've charged my S23 Ultra THREE times on a single charge. Amazing value!

Instead of buying a pack, consider a USB multimeter! They're cheap (<$20) and show the *actual* capacity you're getting, unlike advertised numbers. Knowing the real mAh means you can intelligently pick a *used* pack! Older Anker models are often dirt cheap and still fantastic if you know the actual capacity. Might be more reliable in the long run, too! Does that make sense?