There's an "interview" with Jochen Drees, Bundesliga ref and VAR, who talks about last weekend's incidents in particular.
-He praises the penalty for Schalke as a correct call (something which I still strongly disagree with, as I don't think it crossed the "clearness" threshold for VAR intervention, but I guess that's why I'm not a referee).
-When asked about wrong or wrongfully missed VAR interventions he names two scenes in the Mainz vs Hannover match: 1) Wimmer heading the ball onto his own arm (apparently it didn't merit review, but the ref confirmed his initial ruling anyway) and 2) the penalty that was eventually (and wrongfully) awarded, where he claims communication issues that prevented the ref from being told to watch a replay.
Also a handball penalty in Bremen vs Augsburg, however there he says that the perception of the ref was so strong that the threshold for VAR intervention was very high and inaction was understandable.
-When asked about Berlin vs Frankfurt he says that the ref Daniel Schlager had a clear view on the incident and diagnosed both players pulling at each other, so he decided to let play go on after Jovic went down.
VAR Steinhaus apparently reviewed the footage but because she couldn't find a high enough discrepancy between Schlager's perception of the incident to rule it a clear enough mistake to cross the VAR threshold, even though replays showed good arguments for a penalty.
-He also stresses how important the ref's perception of an incident is, meaning if the referee clearly missed it VAR has a low threshold and the more and clearer he saw the incident the higher the threshold gets.
https://www.dfb.de/news/detail/drees-ein-ueberraschend-unterschiedliches-leistungsbild-196749/
@RW2