The same thing happens with GotR installed. It's only for a few of those billboards though. It's a small price to pay for noticeably improved performance. (Thanks, scanti!)The ad and telemetry removal results in the game no longer fetching generic Ultor billboards to paste on the relevant areas' textures, which leads to them becoming bizarre windows into the game's skybox. I'm sure there's a performance boost as a result, but it might be considered ugly for some (I don't personally mind, but I'm also the sort of person that likes trying to peek out of bounds so I'm biased).
Maybe this doesn't happen to Gentlemen of the Row players, or on some other devices? Feels weird nobody's mentioned it.
These are the only ones I've found: