Worth noting Trump’s approval in this poll is 39/60. Would seem to indicate that Collins is likely to outrun Trump by maybe 3-4 points in November, which is consistent with a close but Lean R race imo. She’s definitely vulnerable, although the RCV aspect probably helps her to some extent.
Unless you are expecting Maine to be a pure Tossup at the Presidential level, Collins outrunning Trump by 3-4 points doesn’t put the race in “Lean R” territory. If it’s anywhere like it was in 2016 with a small but significant Democratic win, the Senate race race is as close to a tossup as can be