This is due to a modification introduced in FP4.SP2J.B.086 which attempts to parry, though only partially, a “ghost inputs” problem that had been making life very hard for certain users. I recommend you read both threads to gain a full understanding of the problem and Fairphone’s “solution” - which of course has affected all users, not just those who were experiencing ghost inputs. The second thread is very long, which underlines how critical this problem is. If you wish to discuss that problem, please do so in the appropriate thread, not here. Thanks 
… And welcome to the forum, by the way 