Most of these would just flat-out not be allowed at my table, since they rely on interpreting the rules in a wonky way.
The real question is: do you really want to be such a poor sport to your DM?
I think that the whiteroom theory optimization threads (and the people that do this work) are actually doing a great service. They are acting as free and unpaid QA* for WoTC and the rest of us!
*Quality assurance, if that doesn't scan for you.
I kid, but only kind of.
Look, I get that there is a thrill in seeing how rules can bend and break- some people enjoy it so much that they turn it into a job. Ahem.
But when we look at these types of threads, I think it is important to remember the following:
1. How realistic is the case? For example, if it can only occur in some crazy MC dip that involves 4 different classes and "turns on" when you're level 12/4/3/1 in them ... well, great to dream about, but you're not going to see it that often. And you need to compare it to what other classes do at level 20.
2. Opportunity cost. If the rules "exploit" requires feats or MC dips or whatever, that means you are giving up other things! There is no free lunch.
3. Result-oriented readings. 5e is written in "natural language," but also uses "specific terms," which somehow combines the worst of both worlds. You read the rules naturally, but also pay attention to sometimes minute differences in specific word choices ... usually involving various adjectives combined with "attack."

4. The "It's not big deal bruh, guys at my high school used to do that all the time," postulate. A lot of the time, a person will announce some exploit with all the subtlety of a youtube video thumbnail showing a shocked woman and a giant red arrow, and when you look at it, it's not an exploit. Just a regular good synergy. It's not punpun- it's a Warlock taking eldritch blast.
5. Finally, if there is a true, insane, OP exploit caused by terrible rules? Well ... thank you to the person who found it, because hopefully that will be corrected at some point. But D&D is a social game. You don't win everything, always, ever. If it is really that insane, you can expect that the table will not allow it. Or, if you bully and ruleslawyer your way into allowing it ... well, D&D is a social game. Reap what you sow and all that.
ETA- I should add that I think that characters from the 2024 PHB are, on balance, more powerful than the 2014 characters. But they are not "OP." And most of the noticeable bumps went to the martials in general (which is good) or to classes that people previously viewed as somewhat lacking (such as monks). The idea that someone might think that a monk with a dagger is now ... OP ... is admittedly kinda funny. DO YOU THINK YOUR WU-TANG SWORD CAN DEFEAT ME?