1. The new evidence would be the lack of positive tests.
2. Nelson Cruz's best seasons were in 2010 and 2015. The fact that he was pacing better production over 53 games in 2020 is not the same thing.
3. You're acting like the only explanation for his production is steroids, which is not true. A simpler explanation would be that Cruz has been a one-dimensional player his entire career who was underrated when he was younger because the baseball metagame was different, and it has just so happened to shift to favor his skills EXACTLY. You might also notice that his wRC+ tracks remarkably well with his BABIP each year -- the past two seasons have been the highest full season marks of his career, roughly 50 points higher than his career average. The two other seasons where he managed a BABIP essentially that high were... 2010 and 2015. If a couple dozen balls landed differently, the story would be way different. If his BABIP was hard-hit fueled and thus NOT luck driven, his career numbers would show it. Further, sabermetric research has shown that the typical career arc for a successful player involves an increase in walk rate over time in exchange for an increase in strikeouts as the bat slows and the approach must become more disciplined to make up for it -- and lo, his walk and strikeout rates have gradually increased over the course of his career.
Where is the evidence that he IS a steroid user? What do you know about how steroids affect baseball players? Even the experts will tell you that we know very little. We know steroids can help athletes build muscle mass quicker -- but strength and power are the one thing Cruz has NEVER lacked, and there's been no sudden change in power production at any point. We also know steroids can help players recover from injury faster, helping them spend more time on the field than they normally would as they age. Nelson Cruz has been remarkably healthy throughout the bulk of his career -- until last year, when he had multiple stints on the IL due to wrist issues.
When you look at his career arc, it tells a story of an all-or-nothing slugger who has the same season over and over with one exception -- his batted ball luck determines whether he has an okay year, a good year, or a great year. It's all tied to his batting average. It's POSSIBLE that he's a steroid user who has simply been able to trick MLB's testing over the course of a fifteen year career -- despite the fact the so many other players with the same resources have failed to do so, and if it were possible, those with the knowledge and technology would be heavily incentivized to sell their services to as many players as possible -- but Occam's Razor strongly suggests otherwise.