Dang I’ve had similar problems when we took over properties as well. The pergo flooring wasn’t installed properly (there were gaps in between the planks) and we ended up having to replace entire units and repair others. We repaired as many as we could but ended up replacing 4 out of 40 units. The gaps were so bad that it was not only unsightly, it was an obvious trip hazard.
My policy has and always will be - Inspect what you Expect. I walk the unit before and after. I identify and mark areas that need attention beforehand, and will literally walk to that area and jump a few times to make sure it’s been repaired. If not, they have to come back and fix it before they can get paid.
My brother rents an apartment in SC and they pushed his move in back a week so they could replace flooring. They failed to address the subfloor issues throughout in the process because they were too cheap. About 11 months into his lease, he stepped on the bathroom floor and his leg went straight through into the apartment below. They repaired that spot only. The downstairs neighbor has complained that their ceiling texture is falling down in the living room under these soft spots - just by him walking on the carpet. I told him to move and report the issues but he’s not good with confrontation and I live 4 hours away so besides telling him exactly what to say (or typing an email that he can copy and paste) there isn’t much I can do for him. I wish more people were as detail oriented as we are!