Core Warlock Traits Primary Ability Charisma Hit Point Die D8 per Warlock level Saving Throw Proficiencies Wisdom and Charis...
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You did not look at what happens in tier3 before asking what is the problem in tier 3 where they have 3 5th level slots per rest plus all of their ADEU abilities .
Also you
literally quoted a link to Crawford talking about hitting the 5th level button again and again and again being a problem wotc acknowledges while citing the spell slot count of a lower level warlock.
See the Crawford clip you skipped, I even quoted him.