That may well be the case where you are. In RFU land it was explained to us by an RFU representative and a Premiership Referee that you could could still play the ball after the ruck formed if you had your hands on it previously and didn't lose contact.
This explains why there is inconsistency in refereeing.
A classic example was dear old Nigel Owens at the 2018 Scotland-England game where he allowed players to jackle for the ball on the ground, after the ruck had formed (in effect "legal" hands in the ruck); thereby ignoring the Law Variation which was in-place at the time.
The 2018 Law couldn't be any clearer; the first person arriving after a tackle can pick up the ball immediately.
As soon as the opposition has arrived (and is competing for the ball by being bound-in, or "attached"), then the Law is very clear: no handling of the ball.
So, if the first person doesn't pick up immediately (not just put hands on) and the opposition have arrived, then the person with hands on the ball must release it and try to ruck over the ball in the traditional manner, hooking the ball back with feet.
The 2018 Law could not be more explicit or clearer.
There's no need to interpret it as the RFU rep & Prem Reff appear to have done back in Apr18.
From the Reff's perspective it's quite straight-forward:
1. Was the tackle legal?
2. Did the first incoming person, after the tackle, pick up the ball immediately (Yes-Open Play, No-Ruck formed)
3. Is someone handling the ball after both teams players have arrived (i.e. ruck formed). Yes=Penalty, hands in the Ruck.