FWIW, I've been using the card since late 2019 and had zero issues with it. There aren't a lot of 2% cards that just straight give you 2% cash back w/o any hoops[1]. The Fidelity card is no muss no fuss for me. 2% just magically appears in my designated Fidelity account at the end of the month.
I have not had to interact with Elan customer service, so I can't speak to that. I also don't care about the Fidelity mobile app (I use fidelty.com from my laptop). I haven't had any issues using fidelty.com to manage the card.
I've had to replace the card once or twice for various reasons and never had any issues. It's a good enough offer that I'm not likely to jump through hoops or create some big other account to improve on. I'm not down to a single account but I've simplified things and diversified.
I used this card for a few months before usbank launched their smartly card, at which point I moved 100k from fidelity to a usbank IRA and now enjoy 4% cash back.
I have not had to interact with Elan customer service, so I can't speak to that. I also don't care about the Fidelity mobile app (I use fidelty.com from my laptop). I haven't had any issues using fidelty.com to manage the card.
[1] https://old.reddit.com/r/CreditCards/wiki/list_of_flat_cashb...