Have you been a naughty Pokemon trainer who was caught using cheats and hacks to gain an unfair advantage over other Pokemon GO players? Of course not, your ban was probably just a huge misunderstanding but you're still willing to repent if given the chance. Well, this may bee your lucky day, provided you just suffered from a soft-ban which still lets you actually log into the game but you're just unable to interact with the environment. Namely, some Pokemon GO players have seemingly found a way to get around this restriction. The method involves a lot of swiping and tapping but is allegedly pretty reliable.
The first thing you have to do if you suspect your Pokemon GO account has been soft-banned is to log into the game and find a nearby PokeStop, then try spinning it. Basically, if it refuses to spin, you've most likely been soft-banned for some reason. Note that this doesn't apply in scenarios in which the game either doesn't load the picture and name of a specific PokeStop or simply tells you to "try again later" which just suggests server issues. No, your PokeStop needs to be in the range of your avatar, fully loaded, and just refuse to spin without any additional messages or explanations. Now, after this happened, you simply have to repeat the same thing 40 times. No kidding, as numerous players online are reporting that the 41st spin attempt is the one which actually succeeds and results in the lifting of the ban.
If this information is 100% accurate—and there's still no confirmation of that—it would almost certainly suggest that the game's soft-ban system may be related to player activity and not just the passage of time itself. In any case, this method is worth giving a shot if you had the misfortune of being banned by Niantic. As for why exactly your account got a soft suspension, note that it probably doesn't have anything to do with external Pokemon GO tracking tools like the recently discontinued PokeVision. Yes, Niantic did describe these tools as "cheat sites" but there's no way for the developer to know which players were using them as they were browser-based. Even if that wasn't the case, it's unlikely the developer would decide to ban millions of fans who didn't outright break the game's rules.