Politeness is often used in a predatory way, like a stranger offering sweets to kids and then insisting it’s impolite to say no.
As for Mr. Pin and Mr. Tulip, all that needs to be known about them at this point is that they are the kind of people who call you “friend.” People like that aren’t friendly.
― Terry Pratchett, The Truth
“Weaponized politeness” = clients counting on you devaluing your work in order not to be “rude”.
It may sound reasonable when the client asks for something impossible, then “relents” and asks you to “meet them in the middle”. It may sound innocent when they ask you for a “little token of goodwill, just a few minutes of your time really” but then refuse to reciprocate.
Either what they ask of you is of little value to them, so it’s rude for them to even ask for virtually no reason – or what they hope to get has some real value for them, and they should be willing to give you at least equal value back.
Your client is not your boss. You don’t have to play their game, you can re-frame the situation, clarify it (they often try this because it usually works, with no actual malice), and then help them see how they could do better next time.
If what you say makes sense to them, the good ones will stay. The bad ones will be offended by your “impoliteness”. Wave those of them goodbye with a smile. For today, you dodged a polite bullet.