No it's not.

Making low power mode automatically turn off is a stupid idea. It's my phone, I know enough to know that during that last 20% there is LITERALLY NOTHING urgent or important enough to waste my portable power bank or cause my phone to take longer charging off the computer or wall.

I want it to charge to 100% as quickly as possible without using fast charging and then we can get back to normal.

There are few things with regards to charging that annoy me as much as realizing my phone switched off low power mode because I hit 80% and now is going to take more time to charge or waste more of my portable power bank. When we were traveling around Japan and spending an entire day using my phone as a camera, navigation, translation, and more, that power and and low power mode were invaluable.

This is a similar problem to the wifi and Bluetooth control icons not actually turning off WiFi and Bluetooth. It says it turns them off until tomorrow but, unless something has changed since iOS 13, the only reason ads would stream and load in an app with cellular data off (that doesn't host them natively) is if it's getting them over wifi. Those icons should, at a minimum, allow a long press to let you chose between "turn off until tomorrow/time or turn off" just like low power mode should be "turn on low power mode until charged to X% or turn on low power mode"