I switched to a paid domain in the last few months and regret not doing it sooner - it just works, and it's nice knowing that I won't have to reconfigure all my stuff to point at a different domain name again in the future. Price was maybe $15/year on porkbun - very much worth it imo.
I've also used freedns in the past and had no complaints about them, except that I think wildcard subdomains are limited to paid supporters (very cheap though) and at the time my SWAG docker image maybe didn't support them? It's been a while. The service was great though. Never had problems like I did with duckdns.
It's a known bug on mobile. You need to return to the main menu, then you can continue your run.
You can't really deselect it on mobile since you're not supposed to be able to select them like this in the first place, afaik.