If accepting a kind word were as simple as it sounds, you'd have managed it by now. Something reflexive is happening faster than your manners can catch up to, and it isn't rudeness or false modesty. It's a system deciding, in real time, that the compliment isn't safe to let in.

Over-apologizing is rarely weakness, and it's almost never really about politeness. It's usually a reflex your system built because, at some point, apologizing did something important — smoothed a moment over, warded off anger, or kept you from being the one who was wrong.

If perfectionism is a character flaw, the work is to force yourself to accept imperfect work — which rarely holds, because you can't argue a protective system out of vigilance by telling it to relax.