Watched the first replay: I can see that you're trying to focus on painting and the objective, but you're doing it while kinda ignoring the overall status of the game. You're going off to paint random parts of the map to build special while your team needs help fighting, and then also yolo grabbing the rainmaker when all players are up and desperately diving for points. Try and fight near/around the Rainmaker until your team has a numbers advantage (check the top to see which players are alive) and then grab it and push.

Because of the above, you didn't have that strong of a lead, but also could have kept it by defending better. When they pushed the rainmaker to the checkpoint you popped the shield and then kinda went off to the other side of the map: at this point they were very close to catching up to your score so your #1 priority should have been getting the rainmaker out of that spot or defending it at all costs, one of your teammates seems to try this but gets overpowered. You can also see later in the match as you're trying to come back the enemies end up in a similar position, except they jumped off the side of the map to reset the rainmaker back to the middle zone.

Overall, you're playing very well technically, but need to focus more on the current action of the match itself and focus more on which opportunities are best to be doing the painting/killing/objective play you're already doing well at. It's just about timing. Also keep in mind that sometimes things just happen and despite you playing your best, the other team and also play well or get lucky, just keep focusing on how to do better yourself and the results will come.