comic fan
I wonder if the issue was Andrew Kreisberg.He was a co-creator and showrunner of the first two seasons of Supergirl and part of season 3 as well as co-creator and showrunner on the early seasons of The Flash(He co-created and produced Arrow and Legends of Tomorrow as well as wrote for all four shows).He was fired for allegations of sexual harassment and physical misconduct.15 women and 4 men accused him.
That's why in Supergirl season 3,the show sort of lost it's way a bit and the back half of the season aired later if you remember.They had to replace him as co-showrunner in the middle of the season.
Here's a article with Melissa about the situation back in 2018.
https://www.cbr.com/supegirl-melissa-benoist-andrew-kreisberg-firing/
Shantel VanSanten who played Patty Spivot in season 2 of The Flash just this past year gave her own accounts of her dealings with Andrew Kreisberg. which led to her Flash role being cut short.She was supposed to be in the whole season but was basically fired by Kreisberg.He was angry she booked another show even though she had arranged and worked out a way to continue on the Flash for the rest of season 2.That's why her exit was so abrupt.Here's a article where she talks about it.
https://tvline.com/2020/10/13/shantel-vansanten-the-flash-season-2-cut-short-patty/
So it wouldn't surprise me if Laura Vandervoort had a poor experience on Supergirl due to Kreisberg.
Yes, this confirms what most fans suspected when Kriesberg was let go for sexually misconduct. Every show that he was a vital part of went south. It's like having a great band but if the writer of your songs is gone then the band isn't as good.
July 20,1969 "The Americans Are On The Moon"
American Land (London Calling: Live In Hyde Park, 2009)