It would be unfair to say this about Mutiny without giving additional context
This is their explanation about why the issue occurs.
They've explained other issues as well here:
https://blog.mutinywallet.com/mutiny-wallet-faq/
Won't be using it for a long time but I will definitely come back when the wallet is hopeful better, as I hope will be the case with Bitkit, Blixt, Zeus, Breez, Muun all of which I've stopped using
I still haven't found THE Lightning wallet that I can use as a primary.