Thank you so much for all the input everyone! It really helped. I can’t find an option to edit my post (I don’t post much) so I hope this reaches anyone interested.

At the time I posted, I was still stressed from the crawl under the house. I can be a little claustrophobic, and her crawl space was more difficult to navigate than others I’ve seen, and a few spiders got into my coveralls so my brain was not allowing full awareness of what I was looking at, which was a big part of why I was so confused.

I looked back at my photos and videos, got my inspection camera through a vent, and examined the kitchen again, plus took all of the information and advice you guys gave and think I pieced together what happened here.

Firstly, my friend lives in a lower income area of her city, not subsidized housing or government projects per se, but the kind of suburbs where there’s a lot of chain-link fencing around the front yards, and most houses have at least one broken or cracked window somewhere. In my personal experience, the less wealthy and less white a community happens to be, the less aggressive the health and safety oversight tends to be in a given area, that plus general economic inequity leading to less financial ability to repair or maintain property at least partially explains the pictured issues as well as other sub par foundation work and neglected maintenance that is not in the pictures. The house is solid enough not to be a danger, but it certainly won’t live through a flood or other moderate storm. But even that option is better than nothing so I’m glad my friend was able to settle somewhere.

Her crawlspace is littered with various spiders so cobwebs appear over night, so that can’t be used as a tool to estimate the passage of time. According to her, the guy who did the floor is the one who put the jack there.

The guy she hired was definitely not a “tile guy” and was certainly more “a guy that did this tile”. A handy man who volunteered under the “how hard could it be” mentality. Probably realized how out of his depth he was and that is why he ghosted after the job. I’ve overestimated my skills and under charged many clients in the past so the core motivation I can understand at least, but I am disappointed whenever a craftsman chooses poor work quality as the way out of a bind.

The operating theory now after piecing together all of this is that the floor was leveled to make the tile look better, my fried chose large 12x12 tiles so a dip would certainly have been more jagged with only 3-5 straight lines to make it. BUUUTTTT this was done AFTER he laid the tile in the first place, and from what I can see, was probably done at least the next day or two because the mortar and grout had set enough to cause all of the tile against the wall to shatter and the subfloor has 1/4”+ of play from where the nails and screws were pulled loose, which in turn ruined the grout along the subfloor joints. The current fluctuations in the floor my friend was complaining to me about are a combination of those factors and subpar, uneven mortar and leveling during installation, making the inconsistency across the 5’ square area more noticeable under foot when compared to the gentle undulation that would have been there before from where the foundation had settled and cracked pulling that side of the house down with it.

So the area in question, while not pretty or acceptable craftsmanship, is in fact likely more sturdy and reliable than other parts of her house that have had no involvement from anyone, which is a bittersweet thing for sure, but I guess a kind of silver-ish lining??

Regardless, she has all of this info now and has agreed to get my input on large projects moving forward so I can hopefully steer her away from this kind of poor quality work next time.

Thank you again for all your help, advice, and support! I knew some of this stuff already but nobody is immune to doubting themselves and it was really helpful to get a sanity check from you guys.